THE ECOLOGY 



OF 


PEAT FORMATION 

V 

IN MICHIGAN. 


A Thesis Submitted to the Faculty of the Department of Literature, Science and the Arts 

of the University of Michigan, for the Degree of 
Doctor of Philosophy 


BY 


CHARLES ALBERT DAVIS. 


LANSING, MICHIGAN 

WYNKOOP HALLENBECK CRAWFORD CO.. STATE PRINTERS 

1907 
















PEAT 


ESSAYS ON ITS 

ORIGIN,USES AND DISTRIBUTION 

IN MICHIGAN 


BY 

v jS 

CHARLES A. DAVIS 

>1 


Published by the State Board of Geological Survey, as a part of the report for 1906, and 
a contribution also to the Biological Survey of the State, author¬ 
ized by Act 250, Session 1905. 


) > > 

', > 


LANSING, MICHIGAN 

WYNKOOP HALLENBECK CRAWFORD CO., STATE PRINTERS 

1907 


13 





In eh a/p "8. 

'Tfu.'vta' \AavLaI .toXf. 


JC S '08 





LETTER OF TRANSMITTAL. 


Office of the State Geologist, 
Lansing, Michigan, November 20, 1906. 

To the Honorable, the Board of Geological Survey of the State of 

Michigan: 

Hon. Fred M. Warner, President. 

Hon. W. J. McKone. 

Hon. Patrick H. Kellev, Secretarv. 

Gentlemen:—I herewith transmit to you for publication in your report 
for 1906, a series of papers on peat, prepared by C. A. Davis, of Ann 
Arbor. They are the fruit of a happy marriage of botany with geology, 
and should not be separated. While on the one hand they are an orig¬ 
inal and important contribution to the botany of peat and the peat 
producing flora, they are of value in many ways to the geologist, and 
to any one interested in the promotion of legitimate industry. In¬ 
formation about peat has been too much left to the one-sided investiga¬ 
tion of the promoter, who, in his over zeal, may ruin a really desirable 
development by over estimates of the profits and under estimates of the 
cost. 

Prof. Davis has endeavored to make clear, in the following papers, 
some of the facts regarding the peat deposits of Michigan which should 
be of practical value to those who contemplate developing such deposits 
for commercial purposes. 

Some of the more important of these facts are: 

That peat deposits are quite variable in structure and origin, but 
their structure is primarily dependent upon the form of the land sur¬ 
face upon which they are found, and the height of the water above this 
while they are being formed. 

That the most important peat deposits and those most likely to be 
of commercial value, are found in depressions, or valleys, which have 
been filled, or partly filled, with peat, through the growth and decay 
of various groups, or associations, of plants, which succeed each other 
in a very definite and orderly manner, according to certain laws of 
plant growth. 

That there are many species of plants concerned in peat formation, 
but of these, the ones growing in the water and a few grass-like plants 
growing slightly above the average level of the water, are much more 
important than any others. 


* 



96 


LETTER OF TRANSMITTAL. 


That there usually is no relation between peat and the vegetation 
growing upon its surface. The character of the vegetation is entirely 
governed by certain laws of plant growth, and primarily by the level 
of the water in the deposit. The surface vegetation generally gives no 
clue to the quality of the peat. 

That Sphagnum moss is not an important plant in peat formation in 
the area under discussion, as it is not present until late in the history 
of the development of any class of peat deposits. 

That certain types of peat deposits are of irregular structure and 
others are free from irregularity, but onlv careful study of sections can 
demonstrate these facts for given deposits. 

Very respectfullv, 

ALFRED C. LANE, 

State Geologist. 


CONTENTS. 


* 


, ; -- j 1 

PART I. 

THE ECOLOGY OF PEAT FORMATION IN MICHIGAN. 

Page 

Introduction.-. 105 

Chemical composition of vegetable matter. 105 

Agents of decomposition of vegetable matter. 106 

Varying rate of action of decomposing agents. 106 

Description and occurrence of peat. 108 

Geographical distribution of peat. 110 

Distribution of peat in Michigan. Ill 

Classification of Michigan peat deposits. 114 

Peat deposits classified according to the form of land surface upon which they have 

been formed. 115 

Classification according to method of development. 120 

Classification according to surface vegetation. 121 

Principles underlying the relation of plants to peat deposits. 128 

The formation of peat in depressions. 130 

(a) In shallow depressions. 131 

(b) Upon flat areas. 134 

(c) In deep depressions, from sides and top. 135 

Effects of consolidation and raising the surface of the deposit. 138 

The water plants and sedges in relation to the peat. 152 

Succession of plants upon the peat after the grounding of the sedge mat. 158 

Some ecological factors which control this succession. 160 

Deposits behind dams. 167 

Conclusion. 170 

Bibliography. 173 


PART II. 

THE FORMATION, CHARACTER AND DISTRIBUTION OF PEAT BOGS IN THE 

NORTHERN PENINSULA OF MICHIGAN. 

OBJECTS OF THE SURVEY. 

Introduction and acknowledgments.'. 183 

Itinerary and areas studied.. 185 

Methods of work on peat. 187 

Types of locality examined.... 188 

General distribution of the plants of Northern Michigan. # . 188 

Soil and topography of the region in relation to the plant societies. 190 

Types of forest. 191 

THE DRUMLIN REGION PEAT DEPOSITS. VALLEY BOGS, THEIR CHARACTERISTICS. IM¬ 
PORTANT PLANT ASSOCIATIONS OF THIS TYPE. 

Partially filled lakes of this area; ways in which they are filled. 195 

Hayward lake. 195 

Pond in peat bog at Nathan. 198 




































98 


CONTENTS. 


Page 

Completely filled lake or basin near Nathan. 201 

Algal lake. ^03 

Merryman’s lake. 210 

Bogs near Hermansville.i. 212 

A mature valley bog. 212 

A cleared bog. 214 

Bogs near Faunus. 214 

PEAT IN THE MORAINAL REGIONS. 

Bogs in sand-plain near Vulcan. 217 

Lake near Menominee river south of Norway..... 219 

Lake Antoine, a large basin beginning to fill. 219 

Sphagnum bog near Lake Antoine, Iron Mountain. 221 

Mature valley bog near Granite Bluff. 223 

Badwater lake, north of Iron Mountain. 224 

Bogs near Bad water lake. 224 

Bogs near Twin Falls. 226 

Lakes near Sagola. 227 

Bogs and lakes north of Crystal Falls. . . .. 228 

A mature bog. 228 

Camp lake, a partly filled lake. 229 

Spring bog near Camp lake.‘. 230 

Bogs near Amasa. 231 

A river-flooded lake. 231 

A mature bog. 231 

Spruce bog at Balsam. 232 

Lakes and bogs in the sand plains south of Crystal Falls. 233 

A rejuvenated sedge bog near Clara lake. 233 

Two shallow lakes in the sand plain. 233 

Deep lakes near Stager.'. 234 

Mature bogs near Maiy lake. 236 

Bog near Iron river. 237 

Mature peat bog north of Bessemer. 238 

Lakes and bogs in the Keweenaw peninsula. 240 

Bogs near Winona mine. 240 

Lake near Winona mine. 241 

Bear lake.. 243 

Buried peat, on the shore of Lake Superior... 243 

Lakes near Marquette. 245 

Lakes and bogs between Newberry and Lake Superior. 246 

The Great Swamp. 246 

Small lake, T. 47 N., R. 10 W. 246 

McLeod’s lake. 247 

Bog at Stuart’s lake. 247 

Lakes at Deer Park Life Saving Station. 248 

Lakes between Grand Marais and Newberry. 248 

Bogs near Trout Lake Junction. 249 

PEAT OF THE SAND DUNES. 

Formation of peat in sand dune areas near Lake Superior at Marquette.. 251 

, Buried peat near Marquette. 252 

Formation of peat in sand dune areas near Lake Michigan at Manistique. 254 

PEAT IN THE HURON MOUNTAINS. 

Types of swamps and bogs.. 262 

GENERAL CONCLUSIONS REGARDING PEAT FORMATION IN THE NORTHERN PENINSULA OF 

MICH. 

Comparison of northern and southern lakes in process of filling. 269 

Important types of filling. 270 

Factors controlling the width of the mat or marginal zone. 271 

Periodicity of growth of the mat... 271 























































CONTENTS. 


99 


THE SPECIES CONCERNED IN PEAT FORMATION. 

Page 


Relation of Sphagnum to peat formation in the Northern Peninsula. 274 

Distribution and abundance of peat. 276 

ECONOMIC CONSIDERATIONS. 

Necessity of careful prospecting. 277 

Other fuels available. 278 

Peat coke in relation to the iron industry. 278 

Agricultural possibilities of the peat bogs. 279 

Other uses to which peat might be put. 280 

List of the common names, and the equivalent scientific names of the plants men¬ 
tioned in this report. 281 


PART III. 

ECONOMICS OF PEAT. 

MISCELLANEOUS USES OF PEAT. 


Introductory. 289 

Uses in agriculture. 289 

Importance of muck soils in Michigan agriculture. 289 

Difficulties in growing crops on muck or peat soils. 290 

Methods used in reclaiming swamp lands. 292 

Peat as a fertilizer. 293 

Stable or barnyard litter on farms. 295 

Peat as a disinfectant for farm use. 296 • 

Peat as stock food..-. 297 

Peat as a deodorizer and disinfectant in towns and cities. 297 

Destructive distillation of peat. 299 

Peat coke and by-products. 299 

Peat gas. 305 

Paper pulp, paper and cardboard. 307 

Woven fabrics from peat. 308 

Packing material. 309 

Roofing and sheathing paper. 309 

Non-conducting packing material. 309 

Paving and building blocks. 310 

As a source of electricity.••. 310 

Peat dye..... 310 


PEAT AS FUEL. 


Historical development of the peat fuel industry in Europe.. . 311 

In America. 313 

In the United States. 313 

In Canada. 313 

In Michigan. 313 

Methods of prospecting. 315 

Prospecting tools. 316 

Final sampling. 316 

Importance of thoroughly proving a deposit. 317 

Factors affecting commercial value of deposits. 318 

Market and transportation. 318 

Area and depth. 318 

Physical condition. 319 

Deep bogs with thin stratum of peat with water or marl below. 319 

Sampling for other purposes than fuel. 319 

Chemical composition and ash. 319 

Possibilities of draining. 320 

Character of the surface growth. 320 

Acidity. 320 


i ) 
) ) > 


/ 


















































100 


CONTENTS. 


Page 


Sources of contamination producing high ash content.. 320 

Importance of ash. 320 

Flooding by streams. 321 

Flooding by rain wash. 321 

Spring and terrace bogs. 321 

Shore wash in lakes. 322 

Mineral matter from water. 322 

In suspension. 322 

In solution. 322 

Precipitated by plants. 322 

(1) Higher plants. (2) Algae. 322 

Relation of deposits of peat to the bottom. 323 

Summary. 324 

Color. 324 

Weight. 324 

Texture. 325 

Relation of ash to commercial value. 325 

Location and extent of peat beds in Michigan. 326 

Fuel value of peat. 332 

Compared with other fuels. 333 

As affected by methods of preparation. 336 

As affected by cost of preparation. 342 

Conclusions. 342 

/ 

MACHINERY FOR THE PREPARATION OF PEAT FUELS AND PEAT LITTER. 

The slayne or slane as used in different countries. 343 

Machinery for making cut peat. 344 

Machines for compressing or condensing peat. 346 

Machines for drying and briquetting peat. 352 

Methods of coking peat. 357 

Machinery for the preparation of peat litter.'. 357 

Devices for carrying peat from bogs to factory. 358 

Peat factories and peat prospects in Michigan. 359 

Conclusion and acknowledgments. 361 



i < 

( c c 


* 


































LIST OF ILLUSTRATIONS. 


PLATES. 

Page 

XIII. A. Section of ditch near Vestaburg showing light colored sphagnum 

over dark peat. 93 

B. Horizontal view in same bog. 93 

XIV. Beaver dam near Negaunee, photograph by R. H. Pettit. 166 

XV. Beaver meadow near Negaunee, photograph by R. H. Pettit. 168 

XVI. Map of swamp distribution,tafter Farmer. 172 

XVII. Map of original vegetation of Upper Peninsula. 182 

XVIIP. Old White Pine forest near Koss, Menominee county. 188 

XIX. Mature conifer bog near Mansfield, rejuvenated. 193 

XX. Sedge marsh on the margin of a sand plain lake. 196 

XXI. Lake margin at Nathan, Menominee county. 198 

XXII. Border of mature bog near Nathan, Menominee county. 200 

XXIII. Pine “Island,” Lake Antoine, near Iron Mountain. 212 

XXIV. North side of lake near Bad water lake. 216 

XXV. Western margin of the same lake as Plate XXIV. 220 

XXVI. Old growth of stunted Black Spruce at Balsam, Iron county. 228 

XXVII. Spruce-Shrub-Sedge bog near Lake Mary. 236 

XXVIII. A. View of peat deposit on rock, Bentley’s camp. Photograph by C. 

Bentley. 260 

B. Black Spruce-Heath Association, Bentley’s camp. Photograph by 

C. Bentley. 260 

XXIX. A peat bog, an old time slane, and an Ames slane. 288 

XXX. Peat fuel. 300 

XXXI. Leavitt peat machinery. 356 


. FIGURES. 

2. Section of bog, after Shaler. 127 

3. Showing structure of peat bed built up from the bottom. 135 

4. Showing how plants fill depressions from sides and top.'. . . . 137 

5. Ideal sketch of Grand Trunk track as laid on the bog at Haslett Park. 154 

6. Map of displacement of track. 155 

7. Sketch of track after new grading. 155 

8. Profile at the same point as figure 5. 156 

9. Sketch map of Algal lake, Menominee county. 204 

10. Ideal section of peat deposit of Algal lake. 209 

11. Plant zones in small lake near Merryman’s lake. 211 

12. Section through a mature peat deposit near Hermansville. 213 

13. Diagram showing way in which Andromeda and Cassandra build out over the 

water in a lake near Stager. 235 

14. Section of a bog north of Bessemer. 239 

15. Section of a bluff with buried peat, shore of Lake Superior, two miles east of 

Portage canal. 244 

16. Buried peat bed near Marquette. 253 

17. Illustrating maintenance of ponds on slopes covered with sand dunes. 259 

18. Peat samplers. 317 

19. Peat cutter after Brosowsky...'. . . 345 

20. Plans and section of peat factory inserted facing page. 347 

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PART I. 


PEAT AND ITS ORIGIN. 


THE ECOLOGY OF PEAT FORMATION IN MICHIGAN. 










ECOLOGY OF PEAT FORMATION IN MICHIGAN. 


Introduction. 

While peat has been commonly used for fuel in northern and western 
Europe from remote antiquity, and its use is still large and apparently 
increasing in Germany, Holland, Russia, Denmark and Sweden, 1 it has 
not been brought to the attention of the people of Michigan until 
recently, that great quantities of this fairly efficient fuel exist within 
the boundaries of the state, as much as one-seventh of its entire area, 
or about 5,200,000 acres, being estimated as swamp or muck land, 2 al¬ 
though not all of this is underlain by peat. The prolonged strike of 
the hard coal miners in 1902-3, followed by the scarcity and high prices 
of all sorts of fuel, taken in connection with the rapidly disappearing 
forests of the state, led to the consideration of all possible sources of 
increasing the available fuel supply, and among these, peat was men¬ 
tioned and its availability investigated. After some preliminary tests, 
at several places in the state, plants were projected for the purpose of 
putting peat into such form that it could be transported cheaply and 
placed upon the market, in competition with other fuel, especially with 
coal. A brief preliminary report upon peat in Michigan, prepared by 
the State Geologist, Mr. Alfred C. Lane, appeared in the Annual Re¬ 
port of the State Geological Survey for 1^02, and to the writer was 
assigned the task of making some more extended investigations into 
the method of peat formation and accumulation, the causes for its 
variations in structure and appearance, and its distribution within the 
state, especially in the Southern Peninsula, and out of these investiga¬ 
tions the present paper has developed. 

In a discussion having the scope attempted here, certain elementary 
principles must be laid down in order that the position of the writer 
may be clear, especially since the paper is intended for the non-technical 
as well as the technical reader, but such statements will be made as 
brief as is consistent with clearness. 

\ 

The Chemical Composition of Vegetable Matter. 

All organic matter, whether of animal or vegetable origin, is made 
up principally of three, or, at most four, chemical elements, of which 
one only, carbon, is a solid, the others being gases. Besides these three 
or four important elements, others, including some of the metallic ele¬ 
ments, are always present in vegetable matter, but only in small quan- 


1 Carter W. E. H.. Peat Fuel; Report of Ontario Bureau of Mines, 1903, p. 193. 

2 Towar’, J. D., Mich. State Ag. College Ex. Station, Bull. 181, p. 157, 1900. 




106 


MICHIGAN SURVEY, 1906. 


titv, and are grouped together as ash in the analyses and may be 
neglected as immaterial in the present paper. 

When uncombined, or only partly combined with oxygen, carbon is 
the most important fuel element, and all forms of fuel have it as a chief 
constituent and are good or poor, as they have much or little of this 
element is available form in them. In vegetable matter, such as wood, 
the leaves and the stems of plants, carbon is associated with two gases, 
hydrogen and oxygen, to form, among others, the complex substances, 
cellulose, or ordinary vegetable fiber (C 0 H 40 O 5 ) and lignin, or woody 
fiber (C 35 H 24 O 20 ). Nitrogen, also a-gas, is present in small quantities 
in certain vegetable substances, associated with the three elements al¬ 
ready named. 

In both cellulose and lignin, as will be seen from the chemical formu¬ 
las, the three elements are built into complicated molecules, having 
many atoms of each, and hence, relatively to the more simple inorganic 
molecules, unstable and easily decomposed. 

Agents of Decomposition of Vegetable Matter. 

When allowed to remain exposed to the air, in the presence of mois¬ 
ture, it is well known that most forms of vegetable matter rot. and 
finally disappear entirely, and such decay has been described as a form 
of oxidation, 1 similar to, if not identical with, that which occurs when 
the same sort of material is burned; that is, as a purely chemical 
process. This process is not, however, directly due to the action of the 
air, or any of its gaseous constituents, or to moisture. Perfectly dry 
vegetable matter will keep indefinitely in the air, as is shown by in¬ 
numerable articles in common use. In like manner, we find that wood 
and similar material of vegetable origin will keep for very long periods 
of time when entirely submerged in water. The decay of vegetable mat¬ 
ter is really a series of complicated changes, due to the growth and 
development of living organisms in the decaying matter. These use 
part of the material of which the vegetable tissue is composed for their 
own nourishment and growth, and thus break it down into simpler com¬ 
pounds. The organisms which thus produce decay are mainly plants of 
simple structure, and often of microscopic size, and when they are not 
so small, their lack of color, and their intimate association with the 
tissues in which they grow, render them very inconspicuous. These 
plants are bacteria and fungi, and are aided in bringing about de¬ 
composition by many types of animals. 

Like all other plants, these decay-producing forms need both air and 
moisture in order to grow, and, moreover, the moisture must be present 
in proper amount, too much water being as detrimental to their growth 
as too little, and where air is excluded they do not thrive. 

Varying Rate of Action of the Decomposing Agents. 

0 

When the conditions are favorable for these plants to grow (that is, 
sufficient moisture, air, and a favorable temperature), they may de¬ 
velop with great rapidity, and bring about quick and complete reduc¬ 
tion of vegetable material to simple gaseous compounds, such as car- 


1 Scott, W. B., Introduction to Geology, 1897, p. 133, 




DAVIS ON PEAT. 


107 


bon dioxid (G0 2 ), ammonia (NH 3 ), and water, and the vegetable mat¬ 
ter as such, ceases to exist. Thus, in moist woodlands, even the hardest 
wood soon becomes rotten, then loses its woody structure entirely, and 
finally vanishes, leaving possibly a trace of dark soil to show that it 
once existed, but nothing that shows that it was wood. The fallen leaves 
in the forest last much less time than wood and soon become indistin¬ 
guishable from the soil of which they become a part. 

If conditions are less favorable the bacteria and fungi do not thrive, 
the decay of wood and leaves goes on more slowly and is less complete, 
so that in wet woods, where the temperature is low, wood and leaves 
may lie for several or many years with little change, and in dry woods 
such debris may accumulate until a thick layer is formed, only the 
lower parts of which are decomposed. If, because of very unfavorable 
conditions, some kinds of the destructive organisms cannot exist, and 
others are reduced in numbers, a slow and partial decomposition may 
take place, in which the more easily broken-down compounds of the vege¬ 
table matter disappear, leaving the more resistant ones almost un¬ 
changed. In such cases, the original mechanical form of the affected 
tissues may be entirely lost, while the chemical composition of the 
larger part of them is only slightly affected, and such changes as do 
take place go on slowly. 

In some cases, where water containing mineral matter, or certain or¬ 
ganic matters in solution, is present in large excess, chemical changes 
not produced by organisms may occur and in such cases it is natural 
that part of the gaseous elements of the molecules which are under¬ 
going change, being chemically more active than the solid carbon, and 
more free to move, should separate from the molecule first, and leave 

the carbon associated with smaller proportions of hydrogen and oxygen. 

* 

What Peat Is. 

From the foregoing considerations it is apparent that vegetable mat¬ 
ter may undergo decomposition under a variety of conditions, dependent 
upon which the amount of change will vary. Some of these conditions 
permit the changes to result finally in complete decay, and in nearly 
complete disappearance of the substances, and others simply allow the 
process to result in the loss of the more easily changed compounds, and 
of the gaseous elements, while the greater part of the material retains 
its original form apd mechanical structure. 

Feat, when examined with a view to determining its origin, will 
usually, even to the unaided eye, show vegetable structure, and fre¬ 
quently well-preserved plant remains will be found in it in large quan¬ 
tity. If decay and disintegration have gone so far that the larger plant 
structures have disappeared, it is still usually possible to identify the 
vegetable tissue-elements, cells, or parts of cells, by the aid of a com¬ 
pound microscope. It is then clearly demonstrable that peat is vege¬ 
table matter which has become partly decomposed. In the process of 
decay, it has been more or less completely changed chemically, and 
usually mechanically, but in such a way that it still retains a large part 
of the carbon, together with more or less of the other more readily dis¬ 
sipated volatile matters which wood and other forms of plant structures 
contain. 


108 


MICHIGAN SURVEY, 1906. 


Description of Peat. 

When dry, peat is of a color varying from a light yellowish brown to 
nearly black, and when wet the shades of color are all much deepened, 
the darker ones appearing quite black. It also varies in texture and 
structure from a loosely felted, slightly coherent mass of plant remains 
having low specific gravity, to a compact, structureless material which 
is relatively heavy, quite plastic and sticky when wet, and which dries 
into firm, tough masses. There seems to be, in general, a close rela¬ 
tionship between the color and texture of different types of peat, the 
lighter colored types being coarser in texture, and approaching ordinary 
dried vegetable litter in appearance, while the darker sorts are nearly 
as structureless as clay. In most deposits of peat which have been un¬ 
disturbed by human agencies, there is a progressive change in color from 
light to darker shades, and, in texture, from coarse and loose, to fine and 
compact, as the bed is cut through from top to bottom. The chemical 
composition of the different types of peat also varies, as shown by the 


* following analyses cited bv 

Ries 1 from 

Johnson. 2 




Material. 

Analyst. 

Carbon. Hydrogen. 

Oxygen. Nitrogen. 

Sphagnum, 

Web sky 

4 4 

49.88 

6.54 

42.42 

1.16 

Peat, porous, light brown, Sphagnum. 

50.86 

5.8 

42’.57 

.77 

Peat, porous, red brown, 

Jaeckel 

53.51 

5.9 

40.59 


Peat, heavy brown, 

4 4 

56.43 

5.32 

38 25 


Peat, dark red brown, well decomposed, 

Web sky 

59.47 

6.52 

31.51 

2.51 

Peat, black, very dense and hard, 

4 4 

59.7 

5 . 7 

33.04 

1.56 

Peat, black, heavy, 1 R t f fnpl 

4 4 

59.71 

5.27 

32.07 

2.59 

Peat, brown, heavy, j - t5est * 01 tue1. 

4 4 

62.54 

6.81 

29.24 

1.41 


From these analyses, which neglect the ash, it is apparent that in 
the denser and darker peats there is a larger amount of carbon and a 
smaller amount of oxygen than in Sphagnum, or in the more porous, 
lighter ‘colored types, amounting to from 8 to 12 per cent increase in 
carbon and from 8 to 12 per cent decrease in oxygen. 

Muck is the name given to dark colored, thoroughly decomposed peats 
in which there is a considerable mixture of mineral matter, but as this 
is very variable in quantity, there is no sharp distinction to be made 
between peat and muck, as all peat contains some mineral matter, 
which appears as ash when the peat is burned. 

In the natural state, peat is always saturated, or nearly saturated, 
with water, except in the uppermost layers, and in very dry times. 

Occurrence. 

Peat usually occurs upon gentle slopes, flat areas, and in more or less 
shallow depressions in the earth's surface, which have either no direct 
drainage, or are poorly drained, so that the surface is always wet or 
covered by water. In these places are formed eventually the accumula¬ 
tions known as “bogs,” “marshes,” and “swamps.” Names for the same 
forms of deposit are “morass,” 3 “moor” 4 and fen, but these, in America, 
are not common terms, or are not in use, and do not need discussion. 
The first three, however, are used so interchangeably that it may be well 
to define them in the sense in which they are used in this paper. The 

\ Ries, H., 21st Report of the New York State Geologist, 1901, pp. r. 58, 59. 

2 Johnson, Peat and its uses. p. 24. 

3 Slialer, N. S., Fresh-water Morasses, of the United States, U S. G. S. 10th An. Report, p. 261. 

4 Coulter, J. M. Plants, Chicago, 1900, p. 187. 




DAVIS ON PEAT. 


109 


writer has not adopted the use of the German word “moor” as a sub¬ 
stitute for “bog," because the English word “moor” is already in use 
with a fairly constant meaning, namely, to designate a broad, flat up¬ 
land with light soil, covered with grasses and shrubs, and while such 
moors may be more or less covered with peat in some cases, they are not 
generally peat deposits. A bog is an area of wet, porous land, on 
which the soil is made up principally of decayed and decaying veg¬ 
etable matter, so loosely consolidated, and containing so much water, 
that the surface shakes and trembles as one walks over it. The vegeta¬ 
tion upon the surface is variable, but it is characteristically either some 
species of moss or of sedge, or grass, or a combination of two or more 
of these with shrubs and even small trees. This is in part identical with 
Cowles' 1 undrained swamp, and is well illustrated by many examples in 
various parts of the Southern Peninsula, of which Mud Lake, in sec¬ 
tions 1 and 12, T. 1 S., R. 5 E., about one and one-half miles west and 
nine miles north of Ann Arbor, the south and east border of Half Moon 
Lake, in Gratiot county, in sections 5 and 6, T. 12 N., R. 4 W., and a 
bog near Hobart Station, 5 miles southwest of Cadillac, on sections 30 
and 31, T. 21 N., R. 9 W., and the region adjacent are types. 

A marsh has a firm soil; that is, not easily shaken when walked upon, 
although it may be soft and very wet, even submerged, and the vegeta¬ 
tion upon it is principally grass-like; that is, with long narrow leaves, 
and weak, short-lived aerial stems. Shrubs may occur upon marshes, 
and where they are present not infrequently form thickets. The de¬ 
velopment of typical marshes is much greater than that of bogs as de¬ 
fined above, and much larger areas of marsh are to be found in more or 
less accessible places. In the southern part of the state, the Detroit 
and St. Clair rivers, the shores of Saginaw bay, in Akron and Wisner 
townships, Tuscola county, and inland, a considerable part of James 
township, Saginaw county (T. 11 N., R. 3 E.), several sections on the 
Ann Arbor R. R., in T. 9 N., R. I W., and considerable areas of the 
shores of the lakes about Lakeland in Livingston county, are examples. 
In marshes of this character the depth of peat may be slight or con¬ 
siderable. 

A swamp, according to the writer’s usage in this paper, has trees 
and shrubby plants as the most important part of the vegetation, the 
soil being, as in the case of the marsh, firm, but wet, even, at times, to 
flooding. The swamps are even more common than marshes and great 
areas of the state were formerly covered by this type of formation, which 
have long since been cleared, drained, and converted into agricultural 
land. One of the most extensive swamps seen in the Southern Penin¬ 
sula of Michigan, by the writer, is located due west from West Branch, 
in Roscommon county, and is traversed by a state road to Houghton 
Lake. The timber in this tract is largely Tamarack, Larix laricina 
(DuRoi) Koch, and Arbor Vitrn, Thuja occidentalis L. Smaller swamp 
areas in nearly natural condition exist in many parts of the southern 
tiers of counties, notably at various points along the rivers, and around 
manv of the lakes which occur here. 

t/ 

These types all intergrade more or less among themselves, and with 
swamps and marshes in which the soil is not of vegetable origin; hence 

1 Cowles, H. C., The Physiographic Ecology of Chicago and vicinity, Bot. Gaz. XXXI, 3, pp. 147- 
154. 


15 




110 


MICHIGAN SURVEY, 1906. 


no absolutely sharp differentiation can be made unless a rather elaborate 
set of compounds be devised. Not infrequently the three types may 
exist in the same basin and, as at Mud Lake, referred to above, it is 
possible to pass from one type to the other in crossing the deposit around 
the lake, and in many other cases around lakes the same relationship 
exists, the bog lying next the lake, the marsh next inshore, and the 
swamps extending back often to the high ground which may have formed 
the shores of the lakes originally. This, as will be seen later, is a per¬ 
fectly normal arrangement, and one easily explained. 

Of the three terms, “bog” is the one most often used in describing de¬ 
posits of peat, but this is perhaps an inheritance from English and other 
European literature on the subject, for in northern Europe the peat is 
very often found in bogs, as described above. 

Since peat is formed on undrained areas or in depressions, the extent 
and depth of a given deposit is generally determined by that of the 
plain or basin in which it lies, but as pointed out by Shaler, 1 it is pos¬ 
sible for the area of peat formation to be extended outward from a center 
under certain climatic conditions by the encroachment of certain species 
of plants which may be good peat formers upon the area occupied by 
those which are not large contributors of vegetable matter. This has not 
been noted by the writer in his studies in Southern Michigan. Since, as 
will be shown later, the conditions for rapid accumulations of peat are 
more favorable in shallow basins than in deep, and in those of limited 
extent than in large, there are many more small deposits than large 
ones, and it is rare to find accumulations of more than fortv or fifty 
feet in depth, although deeper ones are known to exist. 

Geographical Distribution of Peat. 

i 

The conditions favoring the formation of peat are such that it is 
found most commonly in moist and cool or cold parts of the earth, hence 
in northern Asia, Europe and North America it occurs in great abun¬ 
dance, but that it is not lacking in the southern hemisphere is shown by 
the account of the extensive deposits of this substance on the islands 
on the southern coast of South America by Charles Darwin, 2 who states 
that the climate of the southern part of America appears particularly 
favorable to its production. Dies 3 4 states that, “Peat deposits are found 
chiefly in north temperate climates, especially in moist ones. Many 
thousand acres of the North German plain are underlain by deposits of 
peat, while in Ireland alone it is estimated that there are 1,576,000 
acres of flat bog, and 1,254,000 acres of mountain bog. Russia is said 
to have 67,000 square miles of peat land, and there are several million 
acres in Norway and Sweden, while extensive deposits are not lacking in 
France and Holland. Peat bogs are common in New York, Pennsyl¬ 
vania, Michigan, Wisconsin, and Minnesota.” 

Le Conte^ quotes estimates by Dana, that Massachusetts has 15 bil¬ 
lions of cubic feet of peat and also states that California has large areas 
of imperfect peat in the “tide lands” about the mouth of the San Joa¬ 
quin river and elsewhere and that extensive swamps exist in Virginia, 

1 Op. cit., pp. 284-285. 

2 C. Darwin, Naturalist’s Voyage around the world; 1888, pp. 287-288. 

3 Op. cit. p. 65. 

4 Le Conte, J., Elements of Geology. 1896. p. 147. 





DAVIS ON PEAT. 


Ill 


and North Carolina. In Europe 1-10 of the whole surface of Ireland, 
large parts of Scotland, England and France are covered with peat. 
The bog of the Shannon river is fifty miles long and three miles wide, 
that of the Loire in France is 150 miles around. In Canada, according 
to Carter, 1 peat bogs are numerous, and, in extent and wideness of distri¬ 
bution are probably not exceeded by those of any other country of equal 
area. North of the height of land, say 50 miles south of James Bay, 
peat muskeg covers the face of the earth for hundreds, perhaps thou¬ 
sands of square miles, and stretches northward along the westerly 
shores of Hudson's Bay. In the United States it is estimated that there 
are 75,000,000 acres, or 120,000 square miles of swamp land. 

This distribution of peat deposits seems to be due in large measure 
to a combination of factors, among which are abundant precipitation, 
regularly distributed throughout the year, slow percolation and slight 
evaporation from the surface, and small run off of the surface water, be¬ 
cause of poor drainage. There must also be a mild season sufficiently 
long to permit plants to grow with vigor and abundance enough to fur¬ 
nish accumulations of ddbris from which peat may develop. These fac¬ 
tors are all operative in the cold temperate regions of the continents 
mentioned above as areas of extensive peat deposition. They are poorly 
drained, since they have been abandoned recently by the ice of the gla¬ 
cial period, and abound in depressions and broad flat divides, and other 
plains from which the water is but slowly drained by existing streams. 
The growing season is long enough so that the vegetation is luxuriant, 
and in the regions of greatest peat deposition it is cool and moist. The 
soil temperature is low, which tends to hinder percolation from the upper 
to the lower levels of the soil by increasing the viscosity of the soil 
water, while the low average temperature of the air is a check upon 
evaporation from the soil or from water surfaces, since at low tempera¬ 
tures the air is very readily saturated with moisture. The effect of these 
factors is to keep the surface of the soil constantly wet, and to permit 
the water which falls upon it to remain there, and accumulate in all 
depressions. 

Distribution of Peat in Michigan. 

Location: Michigan lies between the parallels 41° 45' and 48° 20' N. 
latitude and between 82° 25' and 90° 34' W. longitude. It is divided 
naturally by the Great Lakes into two distinct parts, the Upper or North¬ 
ern, and the Lower or Southern Peninsulas. The greatest length of the 
northern portion is from east to west and is 318 miles, the width from 
30 to 164 miles. The southern portion has its greatest length from north 
to south, 277 miles, and its width at the widest part is 259 miles. The 
total area of the state is 58,915 square miles, and the coast line is over 
1,600 miles in length. 

Since the - studies from which conclusions have been drawn in the 
present paper were made in the Southern Peninsula, only that part of 
Michigan will be considered in the following brief discussion of the cli¬ 
mate and physiography. 

The fullest account of the climate of the state is by the late Prof. A. 

1 Carter, W., E. H., “Peat Fuel; Its Manufacture and Use,” Report of Ontario Bureau of Mines, 
1903, p. 202. 



112 


MICHIGAN SURVEY, 1906. 


Winchell 1 which still is, in general, correct in its conclusions, although 
many additional data have been collected since its publication. 

Precipitation: Lane 2 gives the average precipitation for this portion 
of the state as some 32 inches, and in the rainfall maps of climate 
^charts of the United States 3 the Lower Peninsula lies in the region hav¬ 
ing between 30 and 40 inches normal precipitation with a small area 
about Little Traverse Bay having over 40 inches. 

The same series of charts show that the precipitation is between 6 
and 9 inches in the first quarter of the year, January to March; be¬ 
tween 9 and 12 inches for the second and third quarters; and between 
0 and 9 inches for the fourth quarter. The period included in these 
charts is from 1870 to 1896. 

The following table cited by Lane 4 from Winchell shows substantially 
the same thing regarding the distribution of the precipitation during the 
year: 

•'ft. 

Distribution of Precipitation in Michigan by Seasons. 


Season. 

Upper Peninsula. 

Lower Peninsula. 

The State. 

Spring. 

19% 

25.8% 

23.8% 

Summer. 

27 

28.7 

28.3 

Autumn. 

28.8 

27.3 

27.7 

Winter . 

22 

19.1 

20 


These data make it appear that the season of greatest rainfall is the 
summer and fall, and as this coincides with the season of greatest heat 
and consequent evaporation, it is evident that this distribution of rainfall 
is an important aid in the peat formation 5 and in the warmer parts of 
the state, may be the primary factor, since it prevents the great drying 
out of the soil moisture which would take place if seasons of long drought 
occurred annually. 

The rainfall is not evenly and uniformly distributed over the South¬ 
ern Peninsula but in the southern part, especially the southwestern, is 
an area of greater precipitation than occurs further north, and the 
valleys of the Saginaw tributaries have less to a marked degree than is 
found elsewhere, except in small areas. The western side of the South¬ 
ern Peninsula has a larger rainfall than the eastern, except a narrow 
strip from the mouth of Saginaw Bay northward. The differences in the 
total amount of rainfall are not however large, and taking into account 
differences in temperature, soil and surface configuration, it is probable 
that there are few areas of the same size in the United States more 
evenly watered than that under discussion. 

Temperature: The average annual temperature of Southern Michigan 
varies nearly 10 degrees in going from the southern to the northern ends 


1 Winchell, A., in Tackabury’s Atlas of the State of Michigan, ed. by H. F. Walling 
2nd. ed. 1884. Proceedings Am. Assoc. Adv. Sci., Troy meeting, 1870. 

2 Lane, A. C., Water Resources of the Lower Peninsula of Michigan, Water Supply 

Papers, U. S. G. S., No. 30, 1899. 1 0 


1st. ed. 1873, 
and Irrigation 


3 Climate Charts of the U. S. Weather Bureau, Washington, D. C., 1900. See also Jefferson 
Report Mich. Acad. Sci., VIII., 1906, and Leverett, F., Flowing wells ami Municipal Water 
plies of the Southern Peninsula of Michigan, W. S. & I, Paper 183 U. S. G. S 1907 p 10 

4 Op. cit. p. 49. ’ 

5 Shaler, op. cit. p. 263. 


Sup- 



















DAVIS ON PEAT. 


113 


of the peninsula, and the same may be said of the average maximum and 
average minimum temperatures, but the isotherms do not run uniformly 
at right angles with the north and south axis of the state but are vari¬ 
ously curved 1 showing that the temperature is profoundly influenced and 
modified, (1) by the presence of the great lakes on three sides of it, (2) 
by the great land mass to the south and the southwest, (3) by the high 
lands in the northern part of the interior of the peninsula. Lake Michigan 
is especially important in its effects, modifying both the maximum and 
minimum temperatures very decidedly and as a result of this the climate 
is more even and milder than that of the region in the same latitude 
west of the lake. Yet the annual range of temperature is about 116° F. 
The range of the average mean temperature of the portion of the state 
under consideration is from 49° at the southern and southwestern parts 
to 41° in the Straits of Mackinaw, the lines of equal temperature bending 
northward in the western and southeastern parts, and southward in the 
high areas in the region northwest and southeast of Saginaw Bay. That 
is, the western and southeastern parts are warmer and the highlands 
cooler than those immediately adjacent to them. 

Sunshine: The amount of direct sunshine a region receives is im¬ 
portant in a discussion of the vegetation of that region, and the following 
has been compiled from the maps referred to above. 2 The Southern Pen¬ 
insula receives, with Wisconsin, part of Illinois, Indiana and Ohio, parts 
of Pennsylvania and New York, and a portion of New England, be¬ 
tween 40%. and 50% of sunshine during the year, compared with less 
than 40% in the Northern Peninsula and more than 70% in the arid re¬ 
gion of Arizona and adjacent territory. 

During January this sinks to less than 20%, in a considerable portion 
of the western part of the peninsula and is only above 40% in the south¬ 
eastern part. The area below 20% is the only one in the United States. 
In July, on the other hand, a very considerable part of the peninsula has 
over 60% of sunshine, the area extending across Indiana into northern 
Illinois to the Mississippi, and constituting the only area with so high a 
total of sunshine east of that river. The rest of the Southern Peninsula 
has between 50% and 60%. The effect of this relatively large amount of 
sunshine, during the growing season should be to increase the develop¬ 
ment of vegetation and to promote its vigorous growth, as well as cause 
a relatively high range in temperature. 

It is thus evident that the Southern Peninsula of Michigan has a suf¬ 
ficiently mild and moist climate to produce abundant plant growth, and 
that the rainfall is so evenly distributed that no long periods of ex¬ 
cessive drought normally occur, but on the other hand, the periods of 
greatest heat are also times of largest precipitation. The differences 
between the average temperature of the southern and northern parts 
are large enough to make a marked difference in the humidity of the 
climate, if the amount of precipitation is approximately the same, be¬ 
cause the air of the cooler region will be constantly more near the sat¬ 
uration point.. In this part of the state, also, the periods of greatest 
heat are shorter and less frequent than in the southern portion, which 
fact is important in considering evaporation effects upon vegetation and 
moist or wet surfaces. That is, in the northern part of the Southern 


1 See Lane, op. cit. pp. 49-53. 

2 U. S. Weather Bureau. Op. cit. 



114 


MICHIGAN SURVEY, 1906. 


Peninsula, because of the differences in temperature alone, more of the 
land surface will be available for the formation of peat than in the 
southern part of the same area, because the drying effects of highly heated 
air are absent there. The efficiency of this agency is relatively greater for 
the higher temperatures than for lower ones, since the capacity of the 
air to "take up moisture increases more rapidly above 50° F. than it does 
below it. 

Physical Features: To these climatic conditions which are, on the 
whole, favorable to the abundant formation of peat, are added certain 
physical surface features which are also very favorable. Shaler 1 says, 
“In the conditions which determine the formation of swamps, the shape 
of the land is generally of most importance.” The Southern Peninsula 
of Michigan is, geologically speaking, new land, recently exposed to the 
erosive agencies which have not yet had time to develop a complete 
drainage system. Because of this, there are great numbers of deep hol¬ 
lows, slight depressions and flat areas, in and upon which water ac¬ 
cumulates and from which it drains away very slowly, or not at all, form¬ 
ing lakes. Moreover, the agencies which shaped a great part of the sur¬ 
face of Michigan, were such that they left it exceptionally rough, after 
entirely obliterating the older surface and its systems of drainage, at so 
recent a time that the new drainage is still in an undeveloped stage. In 
traveling over the Southern Peninsula one is constantly impressed by 
the facts that about its borders, for a varying distance from the Great 
Lakes, the country is quite flat and free from either marked elevations 
or depressions. Proceeding inland however, the character of the surface 
changes and often abruptly, becoming rolling, the plain giving place 
to a series of ridges and hollows, which seem distributed over the land 
without order or plan. Often between areas of such rolling country will 
be found broad plains and valleys, which, though relatively flat, are not 
smooth, but contain frequent depressions in which are found lakes and 
marshes. The broader plains have a somewhat different geological his¬ 
tory from the interior rolling country, but it is sufficient to say that in 
the marginal plains, while rarely considerable deposits of peat are ac¬ 
cumulated, in general such accumulations are shallow and not of com¬ 
mercial extent. In the rough and rolling areas, however, as has been 
pointed out above, there are many undrained depressions and places 
where water stands above the land surface permanently, and in this ter¬ 
ritory, the region of moraines, gravel and till plains, left by the ice of the 
last glacial period, there are very numerous deposits of peat, many of 
which are extensive enough to warrant commercial development, and 
when all the available deposits, large and small, which are to be found 
in this region are taken into account, they represent an enormous amount 
of stored-up fuel. 

Classification of Michigan Peat Deposits. 

Various methods of classification for swamps and peat accumulations 
have been proposed, and more or less satisfactory schemes for grouping 
them may be made. 

Shaler 2 considering all inundated lands, uses a system based upon, 
first, the kind of water by which the land was covered, fresh or salt, and 


Whaler, N. S., Op. cit. p. 263. 

2 Shaler, N. S., Op. cit. p. 264. 




DAVIS ON PEAT. 


115 


then under fresh water swamps, considers the source of the water, 
whether from rivers, lakes, etc. 

Schimper 1 under the paragraph “moors,” states that rich formation of 
peat on wet soils leads to the production of moors, which occupy very 
large areas, especially in the cool and moist districts of the cold temper¬ 
ate belt, and classifies them according as they have or have not a limey 
substratum as “meadow-moors” rich in lime, and “high-moors” poor in 
lime, with the center built up higher than the margins, hence the name. 
The same nomenclature was adopted by Fisher, 2 Fruh, 3 Roller 4 and 
others, and is evidently the ordinary usage in Germany since Eiselen 5 
says that, “in East Friesland, Holland, the Holstein region, etc., they 
usually divide peaty areas into the so-called high and meadow moors.” 

A very casual study of peat bodies will convince any careful ob¬ 
server that not all of them have been formed in the same way, and a lit¬ 
tle consideration of the possibilities of each formation will make it ap¬ 
parent that there may be a number of possible methods by which such 
accumulations have come about. For convenience of discussion the 
writer has grouped the peat deposits of Michigan in several ways, taking 
as a basis of the classification, various points of view and elaborating 
each finder a separate head. 


Peat Deposits Classified According to the Form of Land Surface Upon 

Which They Have Been Formed. 

This seems the most fundamental basis for a scheme of classification, 
and hence is considered first. Peat is formed over: 

A. Depressed surfaces or hollows. 

B. Surfaces not hollowed out. 

Class (A) may be subdivided more or less minutely, but of easily rec¬ 
ognizable forms of closed depressions, the following are most worthy of 
consideration: 

1. Lake basins of the “tarn” type. 

2. Shallow lake basins of the ordinary type. 

<3. Hollows not permanently filled with water. 

4. Hollows in sand dunes. 

5. Hollows formed by dams. 

a. Dams formed by differential uplift or tilting. 

b. Dams formed by hard rock outcrops. 

c. Dams formed by glacial ice, morainal dams. 

d. Dams formed by wave, wind, and ice action along the shores of 

the lakes. 

e. Dams formed by rivers and streams at flood time, cutting off 

portions of their flood plains, or of their channels. 

f. Driftwood dams in sluggish streams. 

g. Beaver dams. 

1 Schimper, A. F. W., Plant Geography upon a Physiological Basis. Trans, by Fisher. 1903. p.657. 

2 Fisher, Chem. Technol. der Brennstoffe, 1897. 

3 Fruh, I., Torf und Dopplerit, Zurich, 1883. 

4 Roller, T., Die Torf Industrie, Wien, 1898. 

5 Eiselen, J. C., Handbuch oder.Anleitung zur.Kentniss des Torf wesens, 

Berlin, 1802. 






116 


MICHIGAN SURVEY, 1906. 


Class (B) may also be subdivided into: 

1. Poorly drained till plains. 

2. Broad divides. 

3. The floors of glacial drainage valleys. 

4. Lake and stream terraces. 

5. Deltas of streams. 

6. Slopes over which seepage spring waters flow. 

7. Northern bogs, in which peat forms on slopes, i. e. “climbing 
bogs.” 

Among the thousands of small lakes in the Southern Peninsula, there 
are several well-marked types, among which two, tarns and ordinary 
lakes, from their frequenc 3 7 , may be cited. These are formed in hollows in 
glacial moraines, or in the depressions which occur so frequently in the 
gravel plains, which mark the lines of drainage from the front of the 
glacial ice. The term “tarn” is applied to any of these small lakes in 
which there is no visible inlet, and such lakes as the “Sister Lakes” a 
short distance west of Ann Arbor, Whitmore Lake, 10 miles north of that 
-city, and Bass and Rock Lakes near Vestaburg, Montcalm county, are ex¬ 
amples of this class. Whitmore Lake is also an example of the type fill¬ 
ing a depression in a plain, as are Rock and Bass Lakes. Many of the 
lakes in Lyndon Tp., T. 1 S., R. 3 E., are excellent examples of morainal 
lakes, and several of these, like Cedar Lake, in section 9, are tarns as 
well. Lakes of the ordinary type, with well marked inlets and outlets 
are so numerous as to need no illustration, since they occur so frequently 
that hardly a portion of the Southern Peninsula, except the region about 
Saginaw Bav, is without them. 

There are abundant illustrations also of the third class of depres¬ 
sions, those not filled permanently with water, especially in the morainal 
parts of the state, which, while they have considerable water in them at 
times are not continuously occupied by lakes and may be termed inter¬ 
mittent lakes in some cases, while in others, they may represent filled 
lakes, or may be merely marshy. Peat accumulates in them, in some 
cases, and in others does not, the general rule seeming to be that in the 
southern part of the state, if shallow, they contain little peat, while 
north, they are usually partly filled with peat, whether shallow or deep. 

The sand dune regions of the Southern Peninsula are chiefly in the im¬ 
mediate vicinity of the Great Lakes, and here between dunes will often 
be found swampy areas, formed apparently by the fact that the dunes 
rest upon a clay substratum, upon which the water which soaks into the 
sand of the dunes, accumulates in sufficient quantities to induce bog, 
swamp or marsh conditions. The shores of Lake Michigan, where not 
too high, the region around Saginaw Bay, and of Lake Huron north of 
that Bay, give numerous examples of this type of depression, while in 
Vassar township, Tuscola county, may be found occasionally a swamp 
which has developed in an inland dune region. 

The types of basins formed by dams are not always easily distin¬ 
guished from other depressions, but frequently the dam itself is still 
easily identifiable, and as the depressions were in many cases originally 
stream valleys they are often long, and narrow in proportion to their 
length. The long narrow lakes on the west shore of the Southern Pen- 


DAVIS ON PEAT. 


117 


insula are, many of them, such stream valleys according to Lane, 1 which 
have been sunk by differential uplift and later closed by bars thrown 
across the mouth of the valley by wind and wave action. In a region so 
generally covered by glacial moraines as the higher parts of the Southern 
Peninsula it would seem easy to point to moraina dams in numbers, but 
relatively few are known to the writer. Such a dam crossed the Huron river 
valley at Ann Arbor at an early stage in the retreat of the Maumee Lobe 
of the ice sheet to the Lake Erie basin, but it was apparently a very tem¬ 
porary affair, and was soon washed out, and this is apparently the fate of 
most of such dams to stream valleys, for we find not infrequently that 
streams have been crossed by moraines which at one time converted their 
valleys into temporary lake basins. Such a dam held back the waters 
of the Cass river near Vassar for a time, and the Pine river near St. 
Louis, and also near Alma, was evidently dammed by small moraines. 
The height of these dams and their looseness of texture was usually un¬ 
favorable to their permanence, for as soon as the water began to run over 
them they rapidly washed out. 

Much more permanent are the barriers, which are built by wave and 
current action and ice shove in the winter, across the mouths of in¬ 
dentations on the shores of the larger lakes, and which tend to straighten 
the shore line by cutting off the bays and making them into independent 
basins. Almost every lake which had originallv anv irregularities in its 
shore line shows some such cut off bav. The best illustrations of dams 
of this type may be found upon the west shore of the state, where wind, 
waves and current action are all working together to straighten the 
shore line, and such lakes as Pine Lake near Charlevoix and Intermedi¬ 
ate and Torch Lakes on the east side of Grand Traverse Bay and a large 
number of others show how efficient these dams are. 

An excellent example of this type of lake on the eastern side of the 
state, is Tobico Lake, in Bay county, a short distance north of West Bay 
City, where the long current-formed sand spit has cut off from the main 
body of water, what was until recently a bay. Here also may be seen, a 
short distance to the west of the present Tobico Lake, and at higher levels, 
two swamps, formed by the filling of lakes, which were cut off in iden¬ 
tical fashion from the main bay during the time when the lakes which pre¬ 
ceded Lake Huron covered the land. Tobico Lake is shallow and sup¬ 
ports an abundant growth of aquatic plants, and is apparently filling 
rapidly. 

These larger examples are cited because they are so conspicuous, but 
Littlefield Lake in northern Isabella county, T. 16 N., R. 5 W., has six 
basins, which have been cut off from the main one, in this case by marl, 
which has closed up mouths of what were formerly bays. The shore of 
Saginaw Bay, especially on the east side, has many small, shallow ponds 
just behind the present shore line, which have been made by the sand 
ridges heaped up by wind and wave action. 

The basins formed by stream action differ in shape and are usually, in 
Michigan at least, of smaller size than those formed by the agencies just 
mentioned. They are of two types, the marginal and the “ox-bow.” The 
marginal type is usually developed on the shoreward edge of the flood 
plain of the stream valley, by the elevation of the bottom of the existing 

1 Op. cit. p. 65. 

16 



118 


MICHIGAN SURVEY, 1906. 


channel of the stream by depositions during seasons of high water. This 
gradually raises the part of the flood plain in which the stream runs, and 
leaves the remoter margins lower, so that when the banks overflow the 
water finds its way to those lower places and remains there, or finds its 
way slowly to the stream lower down in its course. Most streams with a 
wide valley and rather sluggish current show ponds and lakes caused 
by this form of dam in some parts of their course. Maple river, a trib¬ 
utary to the Grand, the Saginaw river, the Pine river, near Alma, and 
many other streams are examples showing this form of dam. The type 
of depression formed by the changes which streams make in their chan¬ 
nels during times of flood is best illustrated by the “ox-bow” lakes, but 
these are by no means the only forms which occur. Streams in the lower 
and flatter parts of their courses, where their valleys are wide and the 
material easily eroded, are most likely to furnish illustrations of this 
form of dam. The streams in this part of their valleys are likely to me¬ 
ander widely and make very tortuous channels for themselves, and in 
flood times, when the current increases in velocity, and ttye amount of 
water is so great that the streams are out of their banks, they cut new 
channels, straighter and more direct, and close up, in part at least, the 
old ones, leaving them as elongated depressions of greater or less extent, 
which are usually wholly or partly filled with water. The Huron river 
below Ypsilanti, and in fact the greater number of the streams flowing 
in broad flat valleys throughout the state, afford examples of cut off 
channels and bends, so that no student of the subject need go far to 
seek illustrations. 

In earlv times in the Southern Peninsula the streams were often 
blocked for considerable distances with dams of drift wood, the trunks 
of trees, washed out from along the banks by freshets, and by the under¬ 
mining of the banks by shifting currents during the ordinary stages of 
water. These were usually cleared out of streams as soon as lumber¬ 
ing began, and, except in the wilder and more inaccessible parts of the 
state, will not be allowed to accumulate again, but the following ac¬ 
count of such dams by Desor 1 is interesting and shows how extensive 
such obstructions formerly were. “We had sailed a day and a half on 
the principal branch of the Manistique, when we were stopped by an ac¬ 
cumulation of tree trunks, forming an obstacle across the river. The 
rafts, which the Canadians called ‘embarras,’ are by no means rare in 
tfle forest, wherever the gradient of the river is slight. A tree trunk up¬ 
rooted by the current, and dragged along by the river catches on the 
side of a meander; if the current does not dislodge it, a second trunk 
coming along is stopped, others come along and their branches interlac¬ 
ing, they end by forming a barrier, which increases indefinitely. There 
are some of these barriers which have a considerable area and are very 
old, since they are often found covered with bushes which have taken root 
upon the floating trunks. The one we encountered here was not of this 
kind; it was evidently of recent formation, because it was not more 
than a dozen fathoms in width. The tree trunks were dry and mainly of 
the Arbor Vitae.” 

Another of these obstructions in the same stream is described as sev¬ 
eral hundred fathoms long and very old, covered by shrubs, among others, 


1 Desor, E., La Foret Vierge, pp. 28-30, Paris, 1879. 





DAVIS ON PEAT. 


119 


the raspberry, which grew “as parasites” on the half rotten trunks of the 
birches and spruces. 

It is not to be questioned that such obstructions in streams did 
much to hold the water back and create marsh and swamp conditions 
for considerable distances above them. 

Of beaver dams little need be said here, since they are discussed at 
length in another place, except to point out that the extensive deposit of 
peat at Capac, seems, in part at least, to have been formed in the ponds 
created by beavers, since their dams were cut through in developing the 
drainage system of the deposit, and that the remains of the animals 
and their dams are frequently found in draining swamps and marshes 
in the central part of the state. 

Types of flat areas belonging to class (B) are widely distributed over 
the Southern Peninsula and only single instances need be cited to show 
the characteristics of each. The “till plain” is a nearly level area which 
probably is the ground moraine of a portion of the glacial ice sheet which 
melted back at a uniform rate faster than the ice advanced, so that no 
morainal ridges were formed. Such a plain of rather small extent is 
found in Washtenaw county north of Ann Arbor. The soil is usually 
bouldery clay and sufficiently impermeable so that the water stands upon 
the more level parts of the surface, a part of the time at least, thus 
tending to cause the development of swamps. 

The broad flat divide between the tributaries of different drainage svs- 
terns is a well marked character of young topography, and is frequently 
found in the Southern Peninsula, in the higher parts especially. Many 
of these divides are parts of till plains, and are swampy for the same 
reason that the plains are. The extensive swamp areas between the Pine 
river and the Maple river in Gratiot county may be considered as exam¬ 
ples of this form of land surface. 

By glacial drainage valleys are meant those in which the water from 
the front of the melting ice sheet flowed away to some lake or to the sea; 
or in some cases they are undoubtedly the temporary outlets of the 
great lakes which accumulated for a time between the front of the ice 
sheet and the high land from which it had recently retreated. These 
valleys are sometimes of great length, and of considerable width, and 
may or may not be occupied by streams at the present time. Such a val¬ 
ley is usually very flat in the bottom, and where it is not too sandy or 
gravelly, In ay become swampy. The series of marshes and swamps ex¬ 
tending southward from Huron county to Imlay City and thence south- 
westward, is sucli a channel, while the well known celery swamp south 
of Ann Arbor and those about Kalamazoo are other examples. 

Lake and stream terraces are often nearly flat and because of being 
covered by impervious clays do not quickly absorb rain water, or that 
which flows over them from higher levels. The wet shores of Saginaw 
Bay, the well marked marshy areas about the western end of Lake Erie, 
and the swamps and marshes upon the terraces of such streams as the 
Saginaw, the Maple and Huron rivers may be taken as typical of these 
forms of plains. 

Streams, besides forming dams along their courses are continually 
depositing material at their mouths by which they build up a more or 
less extensive plain of wet soil to the level of the body of water into which 
they run. These plains are not usually of great extent, but may develop 


120 


MICHIGAN SURVEY, 1906. 


until they fill large areas of the lakes into which they are built. The 
delta of the St. Clair river in Lake St. Clair described by J. Leon Cole, 1 
and that of the Saginaw river are two of the extensive deltas easily ac¬ 
cessible and typical of this form of plain, but in nearly every lake which 
has a stream flowing into it a more or less extensive delta may be found, 
and upon these it will be seen that there are very favorable conditions 
for marsh and swamp development. 

In many places in the Southern Peninsula, clay or compact till slopes 
have at their tops, or superimposed upon them, sand or gravel beds, 
through which the water which falls as rain percolates until it reaches 
the clay. This it follows until it reaches the expanse of clay and running 
over the slopes forms a favorable place for the development of peat. 
Such slopes with bogs upon them occur at Ortonville in Oakland county, 
in the valley of Huron river, north of Ann Arbor, and at a short distance 
west of Chelsea, near the line of the electric railway, and in many similar 
places. 

The northern or climbing bog has not been observed in the area stud¬ 
ied, but the type may occur in the extreme northern end of the peninsula 
and has been reported from the Northern Peninsula by Slialer and 
others. 2 


Classification According to Method of Development. 

A second method of classification of peat deposits may be based 
upon the way in which the deposit was developed, whether from the bot¬ 
tom, or the sides and top, and here again at least two main types are 
to be distinguished. 

(C) Those built up by successive generations of plants, starting 
from what is now the bottom of the peat. 

(D) T*hose which have been formed by growth at the sides, or at 
the top of the basin, or both. 

* Peat deposits of type (C) occur invariably in the shallower depres¬ 
sions, and upon slopes and plains, and since 1 the depth of the water in 
which even aquatic plants will grow is limited to a few feet, it is evi¬ 
dent that no deposit of peat of this kind can be more than this depth, 
unless from time to time the water level is raised, as the deposit is 
built up, or it is formed by floating aquatic plants of the higher types, 
or by algae. 

(D) For the same reason it is clear that the filling of deep lakes 
with peat, so that twenty, thirty or even fifty or more feet of peat may 
be formed, can only take place in relatively few ways, such as: (1) The 
washing of dead and decaying vegetation from the shores into deeper 
parts of the lake basin. 

(2) The drifting in of such matter from the tributary streams. 

(3) Vegetation may grow out from the shores to form floating mats, 
which finally extend themselves to cover the entire water surface. 

It is probable that it not infrequently happens that there may be 
filling from the sides, until the water has become shallow enough to 
enable water plants to attach themselves to the bottom thus formed, and 
from this time on, the building up from the bottom begins, although the 

1 Geological Survey of Michigan, Vol. IX., Part I. 

2 See also Part II of this report. 







I 


DAVIS ON PEAT. 121 

development of peat from the remains of submerged aquatic plants must 
be very slow, because these contain such small amounts of vegetable 
matter relative to the semi-aquatic and land plants. 

(4) In rather rare instances in the southern, and more frequently in 
the northern part, in small, quiet, sheltered bodies of water, floating, 
rootless species of plants may develop in sufficiently large numbers at 
and near the surface to become important factors in the work of filling 
the deeper parts. 

Classification According to Surface Vegetation. 

Still a third system of classification is frequently adopted by pros¬ 
pectors for peat, by botanists, and others, which, while it is purely 
superficial, would, in general, probably be considered as the most 
natural. This is based upon the kinds of plants growing upon the sur¬ 
face of the deposit, and the inference, which has led to much misappre¬ 
hension in this respect, is that the peat below is formed by vegetation 
which at any given time may be growing upon its surface, and is gov¬ 
erned by this in its character. 

In giving names of this sort to peat deposits, usually some conspicu¬ 
ous species of plant, or sometimes more than one, gives its name to the 
formation, despite the fact that many others are associated with it, 
which may be more important as peat formers. Any classification made 
upon this particular basis would include at least the following types 
in Michigan: 

(1) Elm and Black Ash 1 swamps. 

(2) Tamarack swamps, marshes and bogs. 

(3) Cedar (Arbor Vitae) swamps. 

(4) Spruce swamps. 

(5) Willow and Alder swamps. 

(6) Heath (Blue-berry, Cranberry and Cassandra) swamps, marshes 

or bogs. 

(7) Grass and sedge marshes and bogs. 

(8) Rush marshes (Cat-tail and Bullrush marshes belong here). 

(9) Moss bogs (including Sphagnum bogs). 

Elm and Ash swamps are among the most common types of the swamp 
forest of Southern Michigan and may occur in any localitv where the 
drainage is sufficiently poor, whether peat is present or not. In fact, 
it is probably true that this type is less frequently found upon pure peat 
than upon mineral soils, but it may appear as a characteristic forest 
type upon the poorly drained surface of beds of peat, which have become 
thoroughly decomposed, and which are rich in mineral matter. Hence 
in river swamps and delta swamps, on shallow peat approaching muck 
and humus, they are common. On deeper peat they are found at inter¬ 
vals in the margins of the lake swamps, but there seems to be no way 
in which these are to be distinguished from those where the substratum 
of peat is very shallow. 

This association of plants occurs upon peat several feet deep at Half 

1 Throughout this report, at the request of the State Geologist, and as a convenience both to 
printer and the general reader, English names are used for the different species, but in general in a 
perfectly definite sense, and a table of the latin equivalents in specific names for the English names 
used will be found at the end. 



122 


MICHIGAN SURVEY, 1906. 


Moon Lake, in Seville township, T. 12 N., R. 4 W., sections 5 and 6, and 
at Mnd Lake, in the same township, there was formerly an extensive 
forest of this type, now cut off, on peat more than four feet deep. Burns 
reports elm and maple growth (in which the black ash is also an im¬ 
portant constituent) at Dead Lake, upon from 5 to 10 feet of solid peat. 
A very extensive swamp of this general character occurs in sections 7 
and 18 in T. 3 S., R. 4 E., in Washtenaw county, Avhere, in places, the 
peat is more than three feet deep. 

(2) Tamarack is a much more commonly recognized indicator of 
peat deposits than the elm, and is probably a much more certain one as 
well, especially in the southern part of its range, in Southern Michi¬ 
gan, but it is by no means confined to peat deposits. Throughout the 
morainal region, Avherei^er there are undrained or poorly drained areas 
even in the lake plain, there are likely to be found tamarack swamps, 
and hence a few localities only need be mentioned. Xear Ann Arbor 
the type is poorly illustrated by a small area at the First Sister Lake, 
three" miles west" of town. This has been drained and partly cleared, 
but north of the city a few miles are more extensive tracts about the 
small lakes, and in the undrained spots in the vicinity of W T hitmore 
Lake, and from thence north on the line of the Ann Arbor R. R. to 
Durand, they are frequent and typical. Farther north, in Gratiot and 
Isabella counties, they are again numerous, and still farther north, in 
the vicinity of Cadillac, extensive areas are occupied by this type. In 
the borders of lakes the Tamarack frequently is found scattered singly 
or in groups over the grass and sedge marsh, and such a development 
is to be seen in the marshes around Lakeland, Livingston county, espe¬ 
cially in those which lie north of the station a mile or more. In fact, if 
is usually true that the species spreads out into an open marshy area 
near which it may grow, as will be shown later, so that it ma} r be found 
as a characteristic bog or marsh plant anywhere within its range, in 
sufficient numbers to become an important element of the A’egetation. 

The White Cedar, or Arbor Vitae (Thuja occidentalis L.) characterizes 
a type of swamp Avhich is northern in its distribution, and which has 
not been observed bv the writer south of the central part of the state, 
but from northern Gratiot county north, the type occurs with great fre¬ 
quency in lake margins, in springy situations, and along the terraces of 
streams. One of the more southern points at which the type has been 
obseiwed is at Riverdale, Gratiot county, where such a swamp formerly 
occupied a sloping terrace at the foot of a gravelly moraine. The accumu¬ 
lation of peat here was small. At Lake Orion, in Oakland county, is 
another southern locality for this characteristic species, where it occurs 
in association with the Tamarack and the Black Spruce. This illustrates 
a fact which should be constantly borne in mind, namely, that while 
any of these species may occur without admixture of others, in swamps 
which they characterize, they also frequently are found in mixed asso¬ 
ciations, so that a tamarack swamp may be a spruce or a cedar swamp 
as well, or e\ T en an ash swamp. 

As one proceeds northward, the cedar swamp is more and more of com¬ 
mon occurrence, and may indicate extensive peat deposits, or may not. 
At Hobart, in Wexford county, peat was more than 20 feet deep under 

-—--- I __ 

1 Burns, G. P., Formation of Peat in Dead Lake, Mich. Acad, of Science, 6th report, 1905. 





DAVIS ON PEAT. 


123 


a heavy growth of cedar, while at Littlefield Lake, in Isabella county, 
the peat, under equally good growth, Avas, in places, less than two feet 
deep, and noAvhere more than four feet in depth. 

Spruce (Picea Mariana and Picea brevifolia Peck) swamps, like the 
cedar swamps, are of more northern distribution in the Lower Peninsula 
than the Tamarack swamps, but they extend somewhat further south 
than those characterized by the Cedar, occurring in southern Livingston 
and northern Washtenaw counties, either as pure spruce swamps or as 
those in which there is a mixture of Spruce and Tamarack. Such a 
mixed type occurs at Mud Lake, a mile and a half AA^est of Whitmore 
Lake, where both Spruce and Tamarack are scattered over a considerable 
area of deep peat upon the north side of the SAvamp, while the Spruce is 
nearly entirely wanting on the south side. In the region farther north, 
Isabella county and northward, Spruce swamps are of more frequent oc¬ 
currence and are more dense, while in the Northern Peninsula extensive 
areas of this type are characteristic features of the greater part of the 
Peninsula. 

In the southern part of the area under consideration, the Willow 
SAvamp, or marsh, is a common type. In this the ground is more or less 
densely covered by shrubby Willows of various species, often accompanied 
by Poplars, the growth reaching a height of from fAe to tAventy feet, or 
more. The growth may be very dense upon moderately well-drained peat 
or may be scattered upon that which is wet. The Willow SAvamp fre¬ 
quently borders a grass marsh, and the relationship is a genetic one, as 
will be pointed out below. Small WilloAV swamps are common OA r er the 
greater part of the area studied, and are often found occupying the 
swampy areas along streams where there is little, if any, peat. The 
Alder swamp is much like the Willow SAvamp, except that it is usually 
more densely coArered by the bushes, and that these groAv to a greater 
height, and also is more northern in its region of frequent occurrence. 
Like Willows, the Alder is frequently the dominant growth in the wet 
valleys of streams, and in the region north of the central part of the 
Lower Peninsula, Alder swamps are very common, and may deA r elop where 
there is considerable depth of peat. At Mud Lake, mentioned above, is a 
considerable area of Willow swamp near the western end of the peat de¬ 
posit, which has accumulated there. 

Alder is the characteristic shrub in a large peat swamp near Half 
Moon Lake in Gratiot county, and is generally a more or less important 
constituent of the flora of swamps along streams in the region to the 
north of the center of the Lower Peninsula, as well as in the other types 
of swamps. The chief species of Alder found in the Alder swamps of 
this range is A bias incana (L.) Willd., and Avhile both Willows and 
Alders may grow in any Avet open situation, they frequently groAv upon 
the deepest peat. These plants frequently follow clearing, draining, 
burning or destruction by floods of other types of A 7 egetation. 

Another type of bush coA 7 er upon peat deposits, and the one which is 
more likely to indicate peat of considerable depth in the Southern Penin¬ 
sula of Michigan than any other kind of Avoody growth, is that formed 
by the members of the Heath family, of which the Blueberries, Vac¬ 
tinium corymbosum L., and other species of the same genus are the best 
known representatives. Heath SAvamps are rare or absent OA 7 er very 
considerable areas in the lake plain district, and in some portions of the 


124 


MICHIGAN SURVEY, 1906. 


morainal areas, but in others, and upon the till plains in the northern 
and north-central parts of the state, they are of rather frequent occur¬ 
rence. The various heaths are usually associated with the moss Sphag¬ 
num, and the locations cited below will usually serve for both types. 
The association is not invariable, however, and some of the heaths have 
been found in extensive tracts where little, if any, Sphagnum was pres¬ 
ent, as on sections 25 and 2G in Dexter township, Washtenaw county 
(T. 1 S., R. 4 E.). 'Heath swamps are illustrated by a portion of the 
swamp about Mud Lake, already referred to, by a number of areas be¬ 
tween Perry and Lansing, along the line of the Grand Trunk R. R., by 
several examples near Vestaburg in Montcalm county, in the southwest 
part of T. 12 N., R. 5 W., and by others in the vicinity of Boyce Lake, 
Roscommon county, in T. 21 N., R. 3 W. Often with the heaths will 
be found other shrubs, which, in the southern part of the state, may be 
quite as conspicuous, or even more so, but for which it does not seem 
necessary to make a special class here. 

The grass and sedge types of marsh or bog are well known and are 
often called “hay marshes,” because they are cut for hay. The prevail¬ 
ing vegetation is grass-like and may be either sedges or grasses or mix¬ 
tures of the two types, although frequently there are practically no 
species of one or the other of the two present in quantity. Generally 
the sedges are found upon rather wetter situations than the grasses, 
but both grow finely upon peat. The wide “prairies” of Saginaw and 
Bay counties, extending up into Tuscola and Huron are chiefly sedge 
marsh, in which various species of Car ex are the most conspicuous plants, 
but in the same region there are numerous limited tracts in which the 
grasses are the chief vegetation. The marshes of the lake borders of the 
vicinity of Lakeland, Livingston county, and of Four Mile Lake, near 
Dexter, Washtenaw county, and those along the Detroit and St. Clair 
rivers are chiefly sedge marshes, although in most cases, all of these pass 
gradually into rush marshes or bogs as one goes from the shore outward 
to the lake or river. 

As indicated in the preceding statement, the rush swamp or bog is 
wetter than the sedge type in the majority of cases and may be found 
associated with it, and, in the localities named above the rush type is 
found in close proximity, or even intruding upon the other. The 
plants taken as characterizing this wet type of marsh are the Cat-tail 
Flag and the Bulrush, and, as is also true of the sedge and grass marshes, 
both may, and often do, grow in places where there is no peat whatever, 
but, on the other hand, all may grow upon peat of great depth, though 
where these plants are present, the peat is frequently very wet and soft. 

The moss bogs are those in which some species of true moss is a marked 
constituent of the surface cover and rarely may be the only type present. 
The mosses most likely to become dominant in these places" are (1) in 
the wettest places aquatic species of Hypnum; (2) in somewhat dryer 
areas, but still very wet, Sphagnum; (3) in the dryest places in bogs’ or 
after they have been drained, Polytrichum; or, in shady places, the high 
ground species of Hypnum; with Polytrichum not uncommonly occurs 
the lichen Cladonia Sp. The heath bogs mentioned above all have more 
or less Sphagnum present, while the great .peat deposit at Capac was 
densely covered in many places by a species of Polytrichum , as was 


DAVIS ON PEAT. 


125 


the bog (swamp) at Chelsea, Washtenaw county, now being developed 
for fuel manufacture. 

In discussing these schemes of classification it is evident that if the 
discussion is to serve any definite purpose, the life relations of the plants 
concerned in the formation of peat, the principles which govern their 
distribution, not only areal, but also into associations, and their adapta¬ 
tion to environment, must be carefully considered, since in general peat 
deposits have been built up by the continued addition of the dead parts 
of plants which have lived upon the surface of the deposit, while it was 
being built. It must also be borne in mind that not all such plants are 
of equal importance as peat formers, since some of them are of less fre¬ 
quent occurrence, are less vigorous in growth, and because of simple 
structure, furnish less vegetable matter than others. 

The subject of the formation of peat has been written upon fre¬ 
quently for more than a century, but the discussion has been carried 
on mainly by European writers, who have dealt with conditions existing 
in colder, moister and less variable climates than that of the part of 
Michigan which is here discussed, and the developments described are 
evidently quite different from those studied here. 

A brief review of the literature makes this apparent, as shown by the 
following citations: 

Geikie 1 states that “these deposits are largely due to the growth of 
bog mosses and other aquatic plants, which, dying in their lower parts, 
continue to grow upward on the same spot.” “In a thick bed of peat, 
it is not infrequently possible to detect a succession of plant remains, 
showing that one kind of vegetation has given place to another during 
the accumulation of the moss * * * the lowest part of the peat 

may contain remains of reeds, sedges, and other aquatic plants which 
choked the lake. Higher up the peat consists almost entirely of the 
matted fibers of different mosses, especially of the kind known as Bog- 
moss or Sphagnum. The uppermost layers may be full of roots of dif¬ 
ferent heaths which spread over the surface of the bog.” 

Jukes-Brown 2 makes the following statements: “In England and 
Europe generally, some species of moss constitutes the greater part of 
the mass, but elsewhere other plants contribute largely to the growth 
of peat. In the English Fen country, peat is chiefly formed by a moss 
called Hypnum Huitans, but in the mountain bogs of Ireland and Scot¬ 
land the moss is a species of Sphagnum.” 

According to Sir J. Rennie, 3 many of the peat bogs or “mosses” of 
Europe occupy the sites of great forests, some of which have been de- 
stroved in historic times. The fallen timber bv obstructing the natural 
drainage, and causing the ground to become wet and marshy has con¬ 
duced to the growth of mosses which produce peat. 

Brown 4 states that “on the continent (of Europe), turf formation is 
said to be rare on calcareous and frequent on silicious bottoms, though 
in Ireland the rule does not hold true, probably owing to local circum¬ 
stances, not permitting of the water draining away as easily as it does 
in a limestone country generally.” Also that Turf (peat), has received 

Geikie, A., Class Book of Geology, 1890, pp. 82-88. 

2 Jukes-Bvown, A. J., Hand Book of Physical Geography, 1892, p. 211. 

8 Rennie, J., Essays on Peat, p. 65. 

4 Brown, Robert, “Our Earth and Its Story,” Vol. 1, 1887, pp. 60-62. 

17 



126 


MICHIGAN SURVEY, 1906. 


various names indicative of the plants from which it is derived, such 
as ‘moss-turf,’ ‘grass turf/ ‘heath turf/ ‘wood turf/ etc. The Irish often 
speak of a ‘sod’ of peat.” 

Speaking of the peat of Lincolnshire, Wheeler 1 says: “This peat con¬ 
sists of the remains of mosses, water grasses, reeds, flags, and other 
fresh-water plants, common to ditches and ponds, the most abundant 
being the Hypnum duitans and the Arundo Phragmites.” 

Roller 2 makes the statement that “practically all plants except the 
fungi may form peat, but the bog mosses are most important, as owing 
to their spongy nature, they tend to produce a high water level in the 
pond or swamp.” 

Of American writers upon the subject, there are two classes, those > 
who have written as geologists and those who have described the vegeta¬ 
tion upon the surfaces of various types of peat deposits, from the point 
of view of the botanist. 

Desor, 3 quoting from a letter from Lesquereux, gives as the origin of 
Cedar swamps along the Manistique river, the following: “When a 
river overflows its banks, the slimy sediment is deposited, of course, at 
the edge of the current, and where its force ceases; and thus a ridge is 
formed along the banks, behind which, on the retreat of the river, there 
remains stagnant water. This is the origin of peat bogs. The first 
growth of the still water is Chara, a plant of a peculiar composition, 
containing a large quantity of silica, and to the decomposition of which 
I attribute, in a great measure, the formation of the clay found in peat 
bogs. * * * Next to the Chara comes the Sphagnum. To enable 

these plants to grow, requires only a hollow in which moisture can 
lodge and a few fragments of woody fiber.’’ Here follows a discussion 
of the structure, and properties of Sphagnum, and the writer concludes: 
“Upon the basis of these facts, you may easily follow the operations of 
nature in the formation of Cedar swamps.” 

“When a little water remains in a hollow and becomes saturated with 
humic acid by the decomposition of vegetable substances, Sphagnum im¬ 
mediately establishes itself. * * * As these mosses spread * * * 

a favorable soil is formed for the Cedars.” 

Lesquereux 4 later attributed the formation of peat in the Great Dis¬ 
mal Swamp largely to Sphagnum, an observation which later-explorers 5 
dispute. 

The persistence of the idea which Lesquereux advocated, and which is 
evidently correct for northern Europe and a portion of North America, 
is shown by its almost universal restatement in geological text-books 
and by even very recent writers upon peat. This Shaler 6 says: “In the 
northern section of the United States, speaking of those regions in which 
the mean annual temperature is below 55° F., the water mosses, espe¬ 
cially the species of Sphagnum, are by far the most important swamp¬ 
breeding plants. * * * Its value as a peat producer is, throughout 

1 Wheeler. W. H., The Fens of S. Lincolnshire, 2nd Ed. 1896. 

2 Holier, T., Die Torf-Industrie, op. 4-5. 

s Desor, E., in Foster, J. W. & Whitr.ey, J. D., Report on the Geology of the Lake Superior Land 
District, Part 2, 1851. pp. 240-242. 

4 Lesquereux, L., “Torfbildung im grossen Dismal Swamp,” Zeitschr. der deutschen geolog Gesellsch., 
IV, 1852, pp. 695-697. 

sKearney, H.. Report on the Botanical Survey of the Great Dismal Swamp Region. Cont. U. S. 
Nat. Herb. VI, No. 6. 1901, p. 429. 

Also Shaler, N. S., Op. cit. 320-321. 

6 Shaler, Op. cit. pp. 285-286. 




DAVIS ON PEAT. 


127 


the section within the glacial belt, probably greater than that of all the 
other water loving plants.'* 

This writer, to illustrate the importance of Sphagnum as a peat pro¬ 
ducing plant, uses the diagram which we reproduce as Fig. 2—one which 
has been widely reproduced in text-books of geology and elsewhere. It 
should be noted, in connection with this classic figure, however, that 
conditions, such as it represents, with Sphagnum as the mat forming, 
lake covering plant, do not and can not occur in the region here dis¬ 
cussed. The real relation of. plants in the formation of a cover, such as 
is here represented, is shown in Fig. 4 of this paper. 



Fig. 2. Reproduced from Shaler, “Fresh-water morasses of the United States, Tenth Annual Report 

of the U. S. G. S., p. 257. See text and compare Fig. 4. 

Dana 1 says: “In temperate climates it is due mainly to the growth 
of mosses of the genus Sphagnum.” 

Scott 2 has the following: “In northern regions the peat is formed 
principally by mosses, and especially by the bog moss Sphagnum. Else¬ 
where, as in the Great Dismal Swamp of Virginia, the leaves of trees 
and various aquatic plants are the sources of supply. * * * “The 

bogs of northern latitudes are due principally to the bog moss, Sphag¬ 
num, which forms dense and tangled masses of vegetation, dead and de¬ 
caying below, green and flourishing above.” 

Tarr, 3 speaking of the filling of small lakes in the northern states, 
says: “One form of plant is of particular importance in this respect. A 
moss, the Sphagnum, grows luxuriantly on the shores of these tiny ponds 
and lakelets and by its life and death, builds a bog which is sometimes 
several feet in depth.” 

Ries, 4 in discussing the formation of peat says: “Since most peat is 
formed from the moss Sphagnum peat bogs are formed only in cold, 
temperate, humid climates, for the reason that Sphagnum does not 
grow in dry air, etc.” 

Alexander Winchell, 5 on the other hand, as early as 1860, makes the 
following statement: “Around the shallow margins of these lakes is 


1 Dana, J. D., Text book of Geology, 5th Ed. 1897, p. 107. 

2 Scott. B. W., Introduction to Geology, 1897, p. 133-135. 

8 Tarr, R. S., Elementary Geology, 1897, pp. 190-192. 

4 Ries, H., Op. cit. p.r 58. 

6 Winchell, A., First Biennial Report, Geological Survey of Michigan for 1860-1861, p. 130. Also 
see Winchell, Geological Studies, pp. 81-82. ^ 














































128 


MICHIGAN SURVEY, 1906. 


always a belt, abounding in various forms of aquatic vegetation, which, 
decaying, form a deposit of vegetable matters, resting upon the marl, 
from the water’s edge to the inner limit of vegetable growth. With the 
filling of the interior, the shallow belt extends towards the center and 
the vegetable deposit continually encroaches upon the lacustrine area 
until the whole lake becomes a peaty marsh.” 

From the botanists who have written upon the subject, a somewhat 
different idea of peat formation is obtained, namely, that many types 
of plants are concerned, especially water plants. 

Cowles 1 makes this apparent in his discussion of the plant societies 
of the vicinity of Chicago. 

Atkinson 2 intimates it in describing the “atoll moors" of the region 
about Ithaca, N. Y. 

Mills, 3 in a recent paper, points out that “Chara, the water lilies, 
CastaUa and pond lilies Nymphaea, are rapidly reclaiming the bottom 
of a small lake in Indiana. 

Whitford 4 makes an equivalent statement in discussing the swamp 
societies of Northern Michigan. 

Principles Underlying the Relation of Plants to Peat Deposits. 

From these citations it would appear that the writers either had dif¬ 
ferent types of formation in mind, had made merely superficial exami¬ 
nations or had studied the tracts which they have described as fixed 
phenomena. In attempting to reconcile what seem to be conflicting 
statements the writer began comparative studies of the flora of the 
peat deposits of Michigan to see if it were possible to discover any law 
of development by means of which a satisfactory understanding of these 
formations could be reached. In addition to the studies of the flora, 
sections of the peat were made wherever practicable, the remains of 
such plants as could be recognized were studied, and depth of the water 
level below the surface was noted, and, in many cases, the tempera¬ 
ture of the surface and of the subsurface of the soil were taken and 
compared with that of the air above the surface at the same time. 

The following facts were also taken into consideration, which may 
be stated as follows: 

(1.) Relatively very few of the large and more highly organized seed 
plants can grow entirely submerged in water. Of the (nearly) 2,150 
seed plants of Michigan but one Composite, Bidens Beckii Torr., a single 
member of the Campanulaceae, Lobelia Dortmanna L., the majority of 
the Bladderworts, Utricularia species, a few of the Umbelliterm for a 
portion of the season, the greater number of the Water-milfoil family, 
including six species of Myriophyllum and two of Hippurus , one Pro- 
serpinaca , and a single Podostemon, rarely observed have this ability. The 
Cruciferie also have a single representative, Roripa Americana (A. Gray) 
Britt. The Crowfoot family is somewhat more fully represented by two 
species of Batrachiuni, and two of Ranunculus , and the Hornwort familv 

_ _ ' t/ 

Bowles, H. C., Op. cit. pp. 146-147. 

2 Atkinson, G. F., Elementary Botany, New York, 1898, p. 386-7. 

3 Mills, W. Mr, A Physiographic and ecological study of the Lake Eagle (Winona Lake) Region 
Indiana, 28th report. Dept. Geol. and Nat. Res., Ind. Indianaixdis, 1904, p. 380. 

4 Whitford, H. N.. “The Genetic Development of the Forests of Northern Michigan ” Bot Oa 7 

Vol. XXXI, No. 5, May 1901, p. 313-4. s u 

Trans. Kansas Acad, of Science, Vol. 15, 1898, p. 23. 




DAVIS ON PEAT. 


129 


furnishes the well-known Ceratophyllum. The Water Lily family sends 
only its leaves and flowers to the surface or slightly above it, and is an 
important group, having three genera and six species which may be 
counted as members of this class. 

The Endogens furnish a much larger proportion of this type of plants, 
including the important Heter anther a dubia (Jaeq.) MacM., and the 
members of the Naidaceoe, the Pondweed family, including Potamoge - 
ton, but altogether the list is a short ofie when compared with the total 
number of plants. 

(2.) Of these plants which will grow in water, only a few, mainly 
Potamogetons or pond weeds, can establish themselves at a depth greater 
than ten feet from the surface, while the majority of submerged plants 
grow in less than six feet of Avater, unless it is unusually clear. Reed 1 
reports species of Potamogeton reaching down into 18 feet of water, 
and Pieters, 2 in Lake St. Clair, found Potamogetons at about 23 feet, 
as the maximum depth at Avhich any seed bearing plants occurred. 

The writer has frequently tested the depth of the outer limit of the 
growth of the seed plants and has found it to range from 15 to 25 feet 
in many ponds and lakes. As this outer or deeper limit is approached 
the number of species is reduced. The reason for this limitation seems 
to be that the amount of light and heat which is available at greater 
depths is not sufficient for the needs of the plants. 

To the plants which establish themseKes in deep Avater must be 
added the Algte, especially Chara of various species, which grow at con¬ 
siderably greater depths, and which, by their activities, as was pointed 
out by the writer 3 in previous papers, are instrumental in forming 
marl deposits, Avhich raise the level of the beds of lakes, and eventually 
fill them. 

On the other hand there are some species of plants which are able to 
grow luxuriantly in water in which theA r are unable to reach the bot- 
tom, i. e., they grow Avitliout root attachment. These are chiefly 
Utricularias or Bladderworts, and Myriophyllums, and they may be so 
abundant as to cover the entire surface of a small sheltered lake. 
Utricularia vulgaris L., has thus been noted in a number of bays and 
small lakes, and more rarely U. intermedia Hayne, and on one occa¬ 
sion TJ. purpurea Walt, was the species. In exposed lakes these floating 
plants are bloAvn about, and are often thrown up on the shore in con¬ 
siderable quantities, hence in such lakes they are not usually important 
factors in the flora. 

(3.) There are very few plants that groAV partly submerged, which 
Avill grow at a depth greater than six feet, while many of this type, 
and among these,’ the most important of the peat forming species, do 
not grow Avliere the water is over tAVO feet in depth. 

Among the plants which haA T e this habitat are the cat-tail flags, Typha , 
the Bur reeds, Sparganium, especially 8. eurycarpum Engelm., the 
Water-plantain, Alisma plantago-aquatic L., several Arrow-heads, Sagit- 
taria species, some grasses, especially Zizania aquatica L., the Wild or 
Indian Rice, Phragmites phragmites (L.) Karst, Reed-grass, and Panic- 
ularia duitans (L.) Kuntze, Floating Manna-grass. Among the mem- 

3 Reed, H. S., The Ecology of a Glacial Lake. Bot. Gaz. Vol. XXXIV, Chicago, 1902, p. 129. 

2 Pieters, A. J., “Plants of Lake St. Clair,” Bull. Mich. Fish Commission, No. 2, 1894. ; j 

3 Davis, C. A., Jour. Geol. 8 : 485 and 498. Also Report Mich. Geol. Survey, 8 : 66-96. 




130 


MICHIGAN SURVEY, 1906. 


bers of the sedge family are many forms which grow in shallow water, 
the one which reaches the greatest depth being Stir pus lacustris L., 
the Lake Bulrush, which, in Saginaw bay, grows in water more than 
six feet deep. Other important plants of shallow water are species of 
the genera Car ex and Eleocharis, also sedges. The Pickerel-Weed Fam¬ 
ily furnishes Pontederia cordata L., the common Pickerel weed. One 
other important species should be mentioned, although already listed 
among the wholly submerged plants, namely, the Yellow Pond Lily, 
Nymphcea advena Soland, which grows sometimes in water more than 
six feet deep and frequently forms very dense masses of plants of large 
extent, as do also the White Pond Lilies, Castalia sp. 

(4.) Plants which grow on the dry land, or in moist soil, will rarely 
endure conditions where the soil is constantly saturated with water, 
hence they are unable to grow in such places. This seems to be due, 
in part at least, to the lack of available oxygen supply for the roots. 
A few plants growing habitually in wet places, have special adapta¬ 
tions to enable them to get air for their roots, and for other parts 
where it is needed. The best illustration of this adaptation among our 
native plants is found in Decodon verticillatus (L.) Ell. the Swamp 
Loosestrife in which large masses of thin walled tissue, called 
aerenchyma 1 develop on the stem and the pendulous branches where 
they come in contact with the water and apparently serve as aerating 
organs. The thickness diminishes above the water, the tissue changing 
into ordinary cortical tissue. This plant is more fully described in 
another section of this report. In the Tamarack a possible aerating 
system was observed by the writer in 1902 in the swamps where the 
water level was abnormally high. This consisted of very long (some 
a yard or more) root-like organs sent off from the older roots above 
the' water level. Structurally these organs were composed chiefly of 
parenchyma and were very delicate, reddish in color and of varying 
thickness. Other forms of adaptation for this purpose are the large 
air passages which are found in the petioles of the leaves, and in the 
stems of the pond lilies and of many of the rushes and sedges growing in 
the water or in marshy soils. 

(5.) In addition to the sensitiveness to lack of air in the soil, many 
plants are very sensitive to shading, to the presence of injurious dis¬ 
solved substances, such as the ulmic, humic acids, etc., developed by the 
partial decomposition of vegetable matter, and to the constant low 
temperature about their roots, while their leaves are exposed to very 
varying and often high temperatures from the sun’s rays. 

(6.) Yearly all species of plants are affected by a change of climatic 
conditions, growing more vigorously in warm than in cold climates, 
and seem to be less sensitive to shading, as the average temperature of 
the growing season and also the light intensity increases. 

The Formation of Peat in Depressions. 

In considering these few elementary facts of plant growth in their 
relation to the schemes of classification given above, it is evident that 
depressions filled with water to a depth greater than 25 feet, would sel- 

tSchenck, H., Ueber das Aerenchym, ein dem Kork homolcges Gewebe bei Sumpf-pflanzen Prins*- 
heim’s Jahrbucher Bd. XX, 1889. 6 



DAVIS ON PEAT. 


131 


dom or never be filled by plants of a type above the algae, growing from 
the bottom and gradually filling the basins by their growth and decay. 
Such basins must be filled either by the algae, by floating species of seed 
plants with no attachment to the bottom, by sedimentation from 
streams, by accumulation of debris from the shores, or from plant 
growth extending out from the shores, or by combinations of two or more 
of these methods. That is, in general, they are filled from the sides and 
top, if peat is the filling material, and the deep basin, if it were orig¬ 
inally filled with water, must be filled in such a fashion whatever its 
origin, under such conditions as prevail in Michigan. 

Formation of Peat in Shallow Depressions. 

(a) Making application of the principles to shallow depressions, 
it is apparent that if these are less than 25 feet in depth, such plants 
as will grow in water of that depth will establish themselves in the 
deepest parts, and will eventually form a slowly rising deposit upon 
the bottom, assisted by other sediments, which may be derived from 
the tributary streams or from vegetation in shallower parts of the de¬ 
pression. As soon as this has been raised near enough to the surface 
of the water to enable the sliallow-water plants to grow these establish 
themselves, and because of their greater luxuriance of growth, and 
firmer tissues they build up the deposit faster, until the water surface 
is reached, when a still greater number of plants are able to grow. 
When the surface of the deposit has been raised above the water level, 
the conditions are again improved, and again the plants are increased 
in number of individuals and of species, but here a new factor in the 
progress of the up-building comes in, for the dead material is now 
brought into contact with the air, and the heat of the sun, which dry 
out the excess of water, permit the growth of organisms producing de¬ 
cay, and, when a certain amount of elevation above the water level is 
attained, there can be no further building up. because of the drying and 
the thorough decay of all the dead parts of plants which fall to the 
surface. 

No case is ever so simple, probably, as the imaginary one just cited, 
because of the complications which would arise in the course of the 
filling from fluctuations of water level, interference with estab¬ 
lished drainage, and the slow settling of the mass of sediment 

as it was built up, the failure of certain species of plants 

to become established, and the excessive development of others, the 
unfavorable occurrence of certain kinds of soil at the bottom 
of the depression, aiding in this. Thus, in many cases, for some 

cause not known, Cliara seems able to hold the entire bottom of the 
deeper types of lakes and by its growth fills them with marl, upon 
which the seed plants establish themselves very slowly. Such deposits 
are illustrated by Cedar and Marl Lakes in Montcalm county, by Mat- 
tison Lake in Gratiot county, Nich-e-waugh Lake, Sec. 25, Green Oak 
township, Livingston county, and Four Mile Lake in Dexter township, 
Washtenaw county, and many others. In these there are usually large 
areas of shallows upon which no vegetation appears except Chara, 
Scirpus lacustris L., the bulrush and scattering plants of some species 
of Potamogeton, frequently very much dwarfed, together with the float- 


132 


MICHIGAN • SURVEY, 1906. 


ing Utriciilarhi vulgaris L. But eventually from these plants, and by 
the addition of organic matter from other sources, the soil becomes 
less calcareous and later peaty, and then other plants appear, and fill¬ 
ing follows the usual course. At Nich-e-waugh Lake this process is 
now going on around the shores and upon an island of marl upon which 
the water was about a foot deep in June, 1904, and which was nearly 
covered by a growth of Nymphaea advena Soland, the Nuphar or Yel¬ 
low Pond Lily, with which were growing species of Potamogeton, TJtric- 
ularia and Myriophyllum in an impure marl in which the organic mat¬ 
ter was plainly visible. In other portions of the shallows along the 
margin Typha latifolia L., Seri pus lacustris L., and Decodon verticil - 
latus (L.) Ell. had established themselves forming a zone shoreward 
from the Nuphar. 

The water level of this lake was formerly higher than at present 
and upon the gently sloping terrace was a shallow layer of peat, upon 
which, and extending out into the shallow water on to the marl, were 
Typha latifolia L., forming a broad zone and in places mixed with Plirag- 
mites Phragmites (L.) Karst., inshore from which was an open marsh, 
with a shallow substratum of peat, which merged into a Tamarack 
swamp, where the peat was still deeper. 

At Cedar Lake this process of peat formation had been developed un¬ 
til at the time when the land was cleared, the filled portion of the lake 
was occupied by a cedar swamp extending over the entire peaty area, 
upon which the peat was in no place more than three feet deep and 
usually less, while at Marl Lake, less than a mile away, there was an 
entire absence of peat over a great part of the marly shallows, and 
only very sparse vegetation, consisting chiefly of bulrushes, in a few 
spots upon them. 

In other places, parts of the lake where the water is shallow, where 
there is no apparent reason for their absence, plants will not occur. 
The western shore of Bass Lake in Montcalm countv and the north- 

t/ 

eastern shore of Whitmore Lake, in southern Livingston county as well 
as other parts of this lake have very few plants upon them. At Bass 
Lake the soil is very hard and stony which may prevent the establish¬ 
ment of such plants as may get a foothold, while at Whitmore Lake, 
the fact that the plantless area is exposed to strong winds and is sandy 
in consequence, may be an explanation of the lack of vegetation, since 
the waves created by strong winds may prevent some species from get¬ 
ting a start, while ice blown by the winds during the spring may tear 
out others which have started. A soft oozy mud bottom seems much 
more favorable for the growth of many types of water plants than either 
hard clay or shifting sands. This may be due to its more easy permea¬ 
bility, or to the fact that such soils are richer, which, according to 
Pond 1 would increase the growth of water plants. 

From the foregoing it may safely be inferred that as the deposit was 
built up, there would be a change in the character of the vegetation 
as the water decreased in depth and that the plants concerned in the 
formation of the deposit would occupy such places as were suited to 
their requirements in a definite order. The same conclusion would be 
arrived at by studying the plant growth from the margin to the center 


1 Pond, R. H., Report U. S. Fish Commission, 1903. 




DAVIS ON PEAT. 


133 


of any shallow lake which is in the process of filling, for it would be 
found that the plants definitely arrange themselyes according to the 
depth of the water, and if the slope of the bottom is uniform and the 
character of the bottdrn practically the same throughout, the plants 
of given types usually grow in well marked bands or zones, entirely 
around the shores. The descriptions of such lakes are numerous in bo¬ 
tanical literature both European and American and the zonal arrange¬ 
ment of the plants in these locations a well recognized ecological phe¬ 
nomenon. 

In studying a series of such lakes the conclusion must be reached 
that as fast as conditions are favorable, the vegetation of the shoreward 
zones, i. e. that growing in shallower water, moves toward the center, 
and is replaced by that from nearer the shore. This is due not only to the 
shoaling of the water and the increased light which reaches the plants 
growing upon the bottom, but also to increased heat, since the shallower 
water is more quickly warmed than the deeper, to improved aeration due 
to more frequent stirrings by wave and surface current-action, and 
to the improved physical and chemical condition of the substratum. 
In the majority of more than fifty small lakes and ponds studied in 
various parts of Michigan during the present investigation, the order 
of succession of seed plants was as follows: First, in the deeper water 
appeared the Potamogetons, often spreading over the whole central 
part of the lake, as in Rock Lake in Montcalm county, at a low water 
stage a few years ago, and several small lakes seen in Oakland county. 
Shoreward of this was frequently a partial or complete zone of the 
White or Yellow Water Lilies or both. In some small shallow ponds 
the Yellow Pond Lily was found covering the entire surface of the de¬ 
pression with no other plants visible, and at Mud Lake, Washtenaw 
county, both the White and Y r ellow Water Lilies, Castalia tuberosa 
(Paine) Greene, and Nymphaea advena Soland, nearly covered the sur¬ 
face of the remaining parts of the lake but associated with various species 
of Potamogeton and Utricularia. In many cases this group or zone was 
bordered by a wide one of the Lake Bulrush Scirpus lacustris L., in 
which were to be found on the outer margins, the plants of the outer 
zones, and shoreward were the sedges, or frequently, a well marked zone 
of Scirpus Americanus Pers., the “Three Square/’ with some other 
rush-like semiaquatics. At Whitmore Lake the common plant of this 
zone is Eleocharis palustris, R. & S., the Creeping Spikerush. With this, 
some of the sedges, various species of Carex, occur, establishing them¬ 
selves above the water line, the species apparently depending upon the 
kind of soil and the amount of drainage, as well perhaps, as upon the 
accident of becoming established first. 

These characteristic plants were sometimes arranged in limited areas 
rather than zones, or were wanting, or were replaced by other types, 
but they were present so often that they should be mentioned as those 
usually found. 

The movement forward in any zone is in most cases a relatively slow 
one, possibly dependent upon recurring cycles of dry seasons, as is the 
change of condition which makes the movement possible, and on the 
border between two zones occurs a mixture of the characteristic plants 
of the two, to which the term “tension line” has been applied by various 
18 


134 


MICHIGAN SURVEY, 1906. 


writers, in which the shoreward plants are at first in the minority, 
then in about equal numbers and then in the majority, as the shallow 
water type is generally more aggressive. Thus in those lakes where 
the Yellow Pond Lily is abundant, its large, thick and numerous leaves 
resting upon the surface or rising above it, so shut off the light, while 
its large rhizones and spreading roots occupy the soil below, that the 
submerged Potamogetons do not thrive where it is well developed and 
disappear when forced to compete with it, while in those lakes where the 
Yellow Pond Lily is absent, as at Silver Lake, Green Oak Tp., (Sec. 22, 
T. 1 N., R. 6 E.) the Potamogeton may occupy a much wider zone. 

When the surface of the water is nearly reached by the slowly rising 
bottom, and the semi-aquatic types of plants give place, through the 
same sort of competition, to those which can live in moist soils on 
land, for from this time on, during some portions of some seasons, the 
surface of the soil is above water, and plants growing upon it must be 
able to accommodate themselves to this condition of variation of the 


water level. 

Peat Formation upon Flat Areas: In applying the principles stated 
above to the flat, undrained areas, and to wet slopes, a slightly different 
set of conditions prevail, for here during a part of the year the water be¬ 
fore peat deposition begins, may be merely sufficient to keep the soil 
moist or wet, while during the remainder of the time, in rainy seasons, it 
is possible that it may cover the surface in a thin sheet. In such cases, 
the conditions are much like those which exist upon the surface of a filled 
depression, and usually the plants which grow upon the two types of sur¬ 
face are identical in character and often in species. If it is assumed 
that the original surface was bare at the outset, such plants as will 
grow upon wet soils will establish themselves, and, in a relatively 
short time the cover of vegetation causes the drainage to become poorer, 
b,I retarding the run off. The first plants in such cases may be some 
species of Liverwort, like Marchantia, or of moss, like some of the 
Hypnums, and in cool and damp climates, of Sphagnum, while in 
dryer ones it may be rushes, sedges, or grasses at once. This, in turn, 
makes the soil still wetter, and favors the accumulation of vegetable 
matter in a partly decayed state upon the surface of the ground and this 
still more retards the flow of water, until the surface may be covered 
with standing or slowly moving water for a considerable portion of 
the year. These conditions eliminate many species of plants which may 
have established themselves for a time, because they are not able to live 
where the water level is so high, and the suppression of these sensitive 
forms, gives the more hardy species full opportunity, and soon the 
ground is all occupied by species which are adapted to the conditions. 
If the water level is continuously raised as the surface is elevated bv veg¬ 
etable accumulations, these plants will usually continue to form the 
dominant growth and the peat which is deposited will be made up of 
the remains of relatively few species and will be homogenous. The shal¬ 
low beds of peat which are formed in the marshes about Saginaw Bay 
seem to belong to this type, the dominant plant forms being principally 
sedges of the genus Carex, with a few species of grasses associated with 
them. Certain types of terrace and valley peat deposits also belon«- 
m this group, especially those where the terrace or slope is watered 


DAVIS ON PEAT. 


135 


by the water from seepage springs, which are constant sources of sup¬ 
ply. These sedges, frequently Car ex sti'icta Lam. are the chief surface 
plants of these types, and from the hygrophilous (water-loving) char¬ 
acter of these, have probably been so from the beginning of the forma¬ 
tion. In the northern and north central part of the Southern Pen¬ 
insula, some of the mosses, not infrequently Sphagnum, may occur as 
a member of the surface association of plants, along with certain tree 
species, especially the Arbor Vitae. Such an association suggests the 
probability that it represents a mature condition of the deposit, in 
which the water level is not as high as it was in earlier states, but the 
type of deposit has not been carefully studied, and the series traced 
through. 

If, however, there are periods in the growth of the deposit when the 
water level is rapidly raised, and remains high for a time, or is lowered 
and is low for a considerable period, then other types of plants estab¬ 
lish themselves, the original flora is displaced and the deposit will take 
on a heterogeneous character, varying with the type of plant growth, 
and exhibiting well marked stratification, which makes the changes. 



Fig. 3. Diagram showing structure of a peat bed built up from the bottom by successive elevations 

of water level. 


Such changes may be due to the establishment of better drainage or 
to clogging of the drainage outlets, or to the irregular but no less po¬ 
tent, periodicity of rainfall and drought periods, which has been pointed 
out by Harrington, 1 Horton, 2 Rafter, 3 Lane 4 and others. 

The accumulation of peat is a slow process, under any conditions, 
and during the building up of any thickness of it, there will be many 
periods of excessive dryness, or of great rainfall and these would inevi¬ 
tably cause changes in the soil, and the soil water and drainage condi¬ 
tions, sufficient to make radical changes in the flora, provided that they 
were of sufficient duration, periods of at least more than two successive 
years being necessary in most cases to affect a marked change. 

How Depressions are Filled from the Sides and Top: The opposite ex¬ 
treme in the system of classification proposed above, the type of peat de¬ 
posit formed by filling deep basins from the sides and top, furnishes a 
rather more complicated case than any of the others discussed, because 
here the material is accumulated in deep water, and to a considerable ex¬ 
tent the action of the waves and currents must be taken into account. 

1 Harrington, M. W., Bulletin C, Weather Bureau, U. S. Dept. Agric. Washington, D. C. 

2 Horton, R. E., Water Supply and Irrigation Paper No. 30, U. S. G. S. 

3 Rafter, Geo. W., Water Supply and Irrigation papers, No. 80, U. S. G. S. Washington, 1903, pp. 

13-15. 

Lane, A. C., Michigan Geological Survey Report, Volume VII, Part 2, pp. 38-39. 































136 


MICHIGAN SURVEY, 1906. 


The early stages of the formation of such deposits are probably to be 
found in the deeper lake basins which have more or less complete zones 
of aquatic plants, such as those described above, and which may cover 
the shallower parts of the basin, as at Whitmore Lake, Half Moon Lake, 
and others in various parts of the state. These rings of vegetation may 
be broad or narrow according as the slope of the bottom is gradual or 
steep, and the debris from the decay of this, and such fine mineral mat¬ 
ter as is stirred up by the waves, or is brought in by the inflowing 
streams, is spread over the bottom, along the surface of the vegetation 
zones, where it is held by the leaves, stems and roots of the plants, and 
in coves or indentations in the shore line, to which it is borne by The 
more or less constant shore currents, caused by the winds. 

Such deposition as this, however, must be exceedingly slow and ba¬ 
sins in which it is the only method show little filling, even where rela¬ 
tively small and shallow, as in the case of Independence Lake in YY eb- 
ster township, Washtenaw county, Park Lake in the same township, 
and Rock Lake in Montcalm county, which though in the neighborhood 
of filled basins have no considerable deposits of peat. 

In this type of basin where filling has progressed so far that it is 
evident that it will soon be completed, but is still going on, the process 
of filling may be studied. The first marked difference between this and 
the type where no filling has been done, which the basin presents, is a 
marsh of greater or less width, the lakeward extension of which is 
afloat, and which is of the nature of a mat or raft, built up by the inter¬ 
woven rhizomes or horizontal stems of sedges or rushes. These appar¬ 
ently are able to build the mat out from the shore and the filling of the 
water is accomplished under the margin of the mat. 

Superficially the sedges resemble grasses, and in the ordinary or veg¬ 
etative condition are distinguished from them mainly by having, in the. 
kinds more important in this discussion, triangular stems, not prom¬ 
inently jointed nor hollow, while the grasses have hollow, jointed and 
round stems. In addition to these vegetative characters, the fruiting parts 
of the two types are very different. Carex is the most important genus of 
the sedge family, in number of species and is the one furnishing the spe¬ 
cies most efficient in the construction of mats out over the surface of the 
water, and of the genus, the species which in the region studied by the 
writer is by far the most important in this work, is Carex filiformis L. 

This plant is not easily distinguished in the vegetative form, from 
other species of the same genus which grow in similar situtions, but it 
has very long, tough, narrow leaves, tapering to a fine thread-like point, 
which grow from a horizontal, subterranean or subaquatic stem, or rhi- 
zoma, from the nodes of which also grow the long slender roots. These 
underground stems will often grow horizontally more than a foot in 
length in a season, bearing at the end a terminal bud, from which new 
plants rise to send out in turn a new series of horizontal stems. When 
conditions are unfavorable for the rhizomes to grow outward into open 
water, they sometimes grow diagonally downward over the edge of the 
mat, the terminal bud developing just beyond the margin, and thus, 
the mat is strengthened as well as extended by the growth of the plant. 
These stems are tough, buoyant, and very durable, and it is by the inter¬ 
lacing and development of these and their roots that the mat mentioned 


DAVIS OX PEAT. 


137 


above is built up and out over the water. Other plants of the same 
family, and others not related, are occasionally important in building 
similar structures, but the mats formed by these are not so extensive 
nor as firm as those built by the Carcx filiformis. 

Extensive bogs and marshes are formed by these plants by building 
out from the shores of lakes, the felted and interwoven mass of their 
submerged stems and roots making a buoyant structure capable of sup¬ 
porting considerable weight. It is important to note here that the 
sedge can. and does, grow with its rhizomes submerged a foot or more 
below the surface of the water, and with roots extending much farther 
downward. 

The filling of lakes by similar developments has been described bv 
Shaler. 1 2 Ries. - and others, but as the process as noted in Michigan, is 
essentially different from that described by these authors, and is of 
much interest and importance in the region under discussion, the follow¬ 
ing account and illustrations are given: 



Fig. 4. Diagram showing how plants fill depressions from the sides and top. 

Legend to Fig. 4. 1. Zone of Chara and floating aquatics. 

2. Zone of Potamcgetons. 

3. Zone of Water Lilies. 

4. Floating Sedge mat. 

5. Advance plants of conifers and shrubs. 

6. Shrub and Sphagnum zone. 

7. Zone of Tamarack and Spruce. 

8. Marginal Fosse. 


The sedge mat being the most important and the most frequent in 
the region under discussion will be the one chiefly considered, and the 
account below will refer principally to this type. 

It seems probable that the sedges are somwhat dependent upon a 
certain amount of preparation of the parts of the lake over which they 
advance, before they can proceed with their constructive work, because 
the margin of the mat and the water beyond it, are usually occupied by 
a considerable number of species of floating and submerged water 
plants, some of which, like the Xuphar and Potamogetons. have exten¬ 
sive roots and rhizomes, and require some sort of soil in which to grow. 
In other instances the jdants along the margin of the mat are wholly 
unattached, such as the Bladder-worts. Utricularia species. 

It is possible that these plants are the pioneer forms which start the 
building and aid in extending the growth lakeward by furnishing a sort 
of substratum for the roots and rhizomes of the sedges, although in one 
case at least, that of Long Lake, in Fenton township. Genesee county, 
the rhizomes of the Carex were found extending into open water, and it 

1 Shaler. Op. cit. p. 

2 Ries. Op. cit. pp. r. 56-57. 









138 


MICHIGAN SURVEY, 1906. 


seems certain from numerous examinations in various places that the 
mat gets no support from this substratum. The mat is actually floating 
for some distance from its outer margin, because any added weight 
causes it to sink rapidly, while holes through it not only end abruptly 
in water, but the water which pours up through these, wherever the 
surface is weighted down, is clear, and quite free from suspended mat¬ 
ter. Near the lakeward edge, the mats are from a few inches at the 
margin, to about 18 inches or two feet in thickness back where the 
weight of a man may be safely borne. In a series of sections through 
the mat, from the water margin shoreward, the water will be found to 
become more and more full of finely divided matter as one proceeds to¬ 
ward the shore, until, at a variable distance from the water’s edge the 
deposit is nearly solid and the mat no longer floats. 

A studv of the mat itself in the same sections, will show it to be of 
no great toughness, for holes are easily dug with the hands, but the 
material of which it is made is readily seen to be, in all its parts, the 
rhizomes and leaves of the sedges, which retain their structure and 
characteristics throughout the entire thickness of the mat, below which, 
all structure abruptly ceases, even where the mat is grounded. 

This structure makes it evident that the peat deposit is not built 
up by the sinking of the mat under the added weight of the growth of 
vegetation of successive seasons, for in that case there would be a trans¬ 
ition structure from the definitely fibrous and coherent mat, to the 
structureless mass below, and there would be not a space of open water 
between the mat and the rest of the deposit. Therefore the material which 
accumulates under the mat must come from the dropping down of ddbris 
from above, from the under side, and from the margins, in which case it 
may possibly be carried under it by some system of circulation, the 
causes of which need not be discussed here. 

Whatever the causes of this accumulation, as the mat spreads out 
from the shore, at a fairly constant distance from the margin, the peat 
becomes rather dense and solid, so that the bog no longer floats, loses much 
of its quaking character and becomes firm. When this stage is reached,, 
other plants than the sedge and the rushes begin to establish them¬ 
selves upon the mat, and these eventually build up the surface, and by 
shading and overgrowing it destroy the sedge, which is sensitive to shad¬ 
ing. It is possible, however, even after this has happened to show that 
the sedge has done its work by making a section through the superficial 
layers of the deposit to the level where the mat was formerly, for the 
remains of the rhizomes of the sedge may be found at that level in great¬ 
est abundance, as will be shown later. The peat below such a mat is 
usually fine grained, structureless and well decomposed, and nearly 
black in color. 

Effects of Consolidation and Raising the Surface of the Deposit. 

In no other type of peat deposit is it possible to see so clearly the 
marked effects which are caused by a slight change in the level of the 
surface, upon the flora growing above the deposit. As long as the mat 
is afloat the sedge is able to grow freely and keep out all competitors 
except such as grow in the water associated with it. Rarely the mat 
itself is pushed above the water level by being compacted and compres- 
3 ce tl.ii ust in the winter. 




t 


DAVIS ON PEAT. 


139 


When the mat lias become grounded, however, the surface is gradually 
built up until it is above water, at least a part of the 3 T ear, and other 
plants appear in large numbers and in considerable variety, but always 
in a definite order. The number of species is not large for each level 
built up, but when that level has been reached, some or all of the species 
which should be present appear, and these, because of greater vigor in 
growth, in a variety of ways such as height, greater amount of foliage, 
and of roots, etc., usually cause the disappearance of the sedge. While 
the species of Carex mentioned is the most efficient and the most abund¬ 
ant and frequent of the genus in the sedge mats it is not the only one 
which is able to make extensive growths of the sort, Carex aquatilis 
Wahl., C. SartwelMi Dewey, and C. utriculata Boott, all having been 
noted in such mats, either alone or associated with C. filiformis L. 

It is apparent that if the sedge mat, as long as it is afloat does not 
support any considerable number of other types of plants, and if the 
peat is gradually built up under the mat until that no longer floats, 
the sedge is the chief agent in forming the deposit, not even second to 
the water plants which grow in most cases at its outer margin. While 
it is not clear how the consolidation comes about, the present investiga¬ 
tion has led to the conclusion that in no other way than that stated 
can the existing observed facts be accounted for, unless, as suggested 
above, a remarkable and not easily explained circulation exists in the 
water below the mat, by means of which the debris which is formed 
outside its edge is carried under it for considerable distances. This does 
not seem probable, but no final statement can be made at this time. 

Among the lakes visited in which the sedge mat arid attendant phe¬ 
nomena are well illustrated in Mud Lake 1 on the line between sections 
1 and 12, Webster township, Washtenaw county, (T. 1 S., R. 5 E.). This 
is one of a series of depressions in a till and gravel plain lying north 
of Ann Arbor and bordered at the northwest by a strong moraine. 
These depressions are, or have been, occupied by lakes in various stages 
of the process of filling with peat. Of these Mud Lake is probably in the 
most advanced stage before the actual closing and complete covering of 
the waters occurs. The remaining open water is now divided by narrow 
strips of sedge and broken by islands of other plants, and that which 
would be open is well nigh covered with leaves of the pond lilies, Cas- 
talia rcniformis (Paine) Greene and jSfymphaea advena Soland, with 
Potamogeton of various species and other aquatics intermixed. 

In the smaller holes in the sedge mat near the larger spaces of open 
water the Nymphaea is the usual lily, and associated with it are Typha 
latifolia L., the Cat-tail, growing on the shoaler places, Pontederia cor- 
data L. the Pickerel-weed, and Peltandra Virginica (L.) Kuntli., the 
Arrow-arum, which are able to establish themselves in water a foot or 
more in depth upon a very poorly compacted substratum. In places 
along the margins of the open pools the Lake Bulrush was present 
either reaching out over the lily plants or forming clumps which were 
minature islands and occasionally small groups of Decodon verticil- 
latus (L.) Ell., the Swamp Loosestrife, grow in the margin of the sedge 
mat, or forming small clumps in the shallow water. These islands are 
evidence that the bottom of the pools is not very far from the surface 


1 Since the following account was written, a description of this locality has been printed. See 
Pennington, L. H., “Plant Distribution at Mud Lake.” Report Mich. Acad, of Sci., Vol. VIII, 1906. 





140 


MICHIGAN SURVEY, 1906. 


in the places in which they occur, although it may be much deeper in 
areas where other plants occur. 

The sedge mat upon the south and east sides has a very different 
character upon the shoreward margin from that of the north, but upon 
the lakeward areas it is very similar all around to the open water ex¬ 
cept as noted below. It is wide, very wet, the sedge plants grow¬ 
ing in from 8 to 12 inches of water, floating, so that it is strongly 
shaken when walked upon, and for several hundred feet back from the 
open water the principal plant species present is Carex filiformis L. 
with which is associated in the wettest places—often small depressions 
among the sedge plants—a few surviving and stunted plants of the Yel¬ 
low Pond Lily, and in the water, oversliaded by the sedge culms and 
leaves, is abundant Utricularia intermedia Havne, which is a common 
plant also in open water as well. With this are algae, and the min¬ 
ute seed plants Lenina, frequently L. trisulca L. 

In addition to these a more conspicuous plant was Typlia latifolia L. 
which was scattered all over the marsh and entirely replaced the sedge 
at the east end and upon the west and northwest sides of the lake. In 
some places back from the edge of the mat, where the Typlia is found 
in the marsh, the turf seems firmer than in others, but in general the 
conditions where this plant is found are quite as wet or wetter than in 
the pure sedge mat. 

A conspicuous plant upon the sedge marsh and somewhat com¬ 
mon with the Typlia and one of some significance with regard to 
the dryness of the substratum, i. e. the height of the water level, is the 
Marsh Shield-fern, Dryopteris Tlielypteris (L.) A. Gray, which, al¬ 
though it is found in the young stage in the western part of the sedge 
mat, where the sedge plants are somewhat scattered, is the dominant 
plant upon the areas of the mat where for some cause the surface level 
is very slightly higher and the turf firmer and more compact,' possibly 
from ice thrust in the winter or the accumulation of drift material on 
which the sedge plants do not thrive, or are absent altogether. 

This fern is very light green in color, in this kind of situation, so its 
position is easily seen, and it is usually accompanied by quite an ex¬ 
tensive flora which has reached out from the more stable, open and bet¬ 
ter drained marshes near the shore, and with these, in low spots, usually 
are remnants of the aquatic and semi-aquatic vegetation which the 
sedge has not crowded out completely. The plants of this association 
which are from the shoreward regions, are: 

Boehmeria cylin drica (L.) Willd., False Nettle. Very common. 

Eupatorium purpureum L. Joe-Pye Weed. 

Eupatorium perfoliatum L. Thoroughwort. 

Aster jnnceus Ait. Rush Aster. 

Lycopus communis Bicknell. Bugle-weed. 

Larix Laricina (Du Roi) Koch. Tamarack. 

Osmunda regalis L. Flowering Fern. 

Galium spp. Bedstraw. 

Triadenum T irginicum (L.) Raf. ( Elodes companulata Pursli) 
Marsh St. John’s wort. 

Impatiens biflora Walt. Spotted Touch-me-not. 

T iola alsophila Greene (Viola blanda palustriformis A. Grav.) 
Marsh White Violet. 


DAVIS ON PEAT. 


141 


Carex limosa L. Mud Sedge. 

Ophioglossum vulgatum L. Adder's Tongue Fern. 

Limnorchis hyperborea (L.) Rydb. ( Habenaria hyperborea R. 
Br.) Tall Leafy Green Orchis. 

The list of those from shallow water is smaller and includes the fol¬ 
lowing : 

SagittaHa latifoHa Willd. ($. variabilis Engelm.) Broad-Leav- 
„ ed Arrow-Head. 

Peltandra Virginica (L.) Ivunth. (P. undulata Raf.) Arrow- 
arum. 

Typha latifolia L. (not common here.) Cat-tail. 

Carex filiformis L. Slender Sedge. 

This list is given because of the fact that most of the species from 
the shoreward group are quite constant in their association with the 
marsh shield fern, and, while all of them are not invariably found with 
it, in such places, some of them are, and they undoubtedly help prepare 
the surface of the sedge mat for succeeding plant associations. The 
Tamaracks which are found with the ferns thus far out upon the bog 
are usually of small size and quite young, but as soon as they get tall 
enough to produce shade they are accompanied by a less number of 
species, some of them evidently persisting from the open fern associa¬ 
tion. 

Under a group of young Tamaracks, which were 8 to 10 feet in 
height, and formed a rather dense thicket 10 to 15 feet in diameter, 
somewhat farther shoreward than the most advanced stations of the 
ferns, the following species were found and the association is typical 
on this sort of growth: 

• Dryopteris Thelypteris (L.) A. Gray. Marsh Shield-fern. 

Viola alsophila Greene. Marsh White Violet. 

Onoclea sensibilis L. Sensitive Fern. 

Menyanthes trifoliata L. Buck-bean. 

And little else, the shade being quite dense. The Dryopteris in these 
thickets was much taller and larger and of darker green than that in 
the open bog. 

In some of the areas of fern it was evident that another change had 
begun, for upon these were small and apparently recently established 
colonies of Sphagnum, practically the only growth of the moss upon 
the south and east sides of the entire marsh area. Still farther towards 
the shore the areas of fern were somewhat less numerous and the sedge 
became more dense and taller, and the surface of the marsh seemed a 
little lower, with more water upon it. Here the Carex filiformis was 
mixed with two other species, possibly more, but certainly with Carex 
Sartwellii Dewey, SartwelPs Sedge and some Carex teretiuscula Good, 
the Lesser-Panicled Sedge. 

Here also were found associated with the sedges, more or less fre¬ 
quently, Menyanthes trifoliata L. and Comarum ( Potentilla ) palustre 
(L.) Marsh, the Marsh Cinquefoil. 

Bordering this area and extending along the vdiole length of the 
19 


142 


MICHIGAN SURVEY, 1906. 


south and east sides of the marsh was a narrow zone of shrubby wil¬ 
lows of several species, and immediately back of this, away from the 
marsh, was a belt of tamaracks, several rods, or even more, in width. 
The plants found beneath the tamaracks which were from 20 to 40 feet 
in height, were as follows. In considering this list it must be remem¬ 
bered that the water level is below the surface of the roots of the trees, 
and some of the shrubs, so that these form elevated stools, covered 
with sufficient soil to give root-hold to various plants, hence so far 
as water level and drainage is concerned the species may have a con¬ 
siderable variety of habitat in what is often treated as a single type. 
No attempt is here made to indicate the water relation of the different 
species, although some species seemed practically confined to the low 
hummocks formed by roots and stumps, and others to the depressions 
between these; all were well within the shade of the tamaracks and 
were thrifty in this situation. 

Woody Plants of the Tamarack Zone. 

Acer rubrum , L. Red Maple.. 

Betula pumila L. Dwarf Birch. 

Comas stolonifcra Mx. Red Osier. 

Comas candidissima Mill. Panicled Cornel, or Dogwood. 

Gaylussacia rcsinosa (Ait.) T. & G. Huckleberry. 

Ilex verticillata (L.) A. Gray. Black Alder. 

J uni perns communis L. Ground Juniper. 

Picca brevifolia Peck. Black Spruce.. 

Rhus Vernix L. (Rhus venenata D. C.) Poison Sumach. 

Rosa Carolina L. Swamp Rose. 

Rubus Americanos (Pers.) O. A. F. Dwarf Raspberry. 

Eolanum Dulcamara L. Wild Potato. Nightshade. 

TJlmus Americana L. White Elm. 

Oxy coccus Macrocarpus (Ait.) Pers. ( Vaccinium Macrocarp on 
Ait.) Large Cranberry. 

The Maples, Elms and Spruces were all small, the shrubs mostly well 
developed plants, but not old or large. Of herbs, the following list con¬ 
tains the most prominent species, and those which are probably most 
significant in the history of the development of peat. 

Dryoptcris Thelypteris (L.) A. Gray. Marsh Shield-fern. Here 
very abundant and thriftv. 

Boclimcria cylindrica (L.) Willd. 

Carcx sterilis ccphalantha Bailey. (C. cchinata cephalantha 
Bailev.) Prickly Sedge. 

Carcx Icptalca Wahl. (C. polytrichoides Willd.) Bristle-stalked 
Sedge. ' 

Carex tenella Schk. Soft-leaved Sedge. 

Car ex trisperm a Dewey. Three-seeded Sedge. 

Coptis trifolia (L.) Salisb. Goldthread. 

Equisctum tiuviatilc L. (E. limosum L.) Swamp Horsetail. 

Eriophorum polystachyon L. Tall Cotton-grass. 

Galium trifidum L. Small Bedstraw. 


DAVIS ON PEAT. 


143 


Glyceria nervata (Trin.) Nerved Manna-grass. 

Panieularia nervata (Willd.) Ivtze. 

Impatiens biflora Walt. (/. fulva Nutt.) Spotted Touch-me-not. 

Leptorchis Loesellii (L.) Mac M. (Liparis Loesellii Rich.) Fen 
Orchis. 

Unifolium Cana den sc (I)esf.) Greene. (Maianthemum Ganadense 

Desf. False Lilv-of-the-Vallev. 

*/ «/ 

Menyanthes trifoUata L. Buck-bean. 

Osmunda cinnamomea L. Cinnamon Fern. 

Osmunda regalis L. Flowering Fern. 

Gomarum palustre *(L.) Marsh. (Potentilla palustris Scop.) 
Marsh Cinquefoil. 

Rumex Britt anica L. Great Water-dock. 

Sarracenia purpurea L. Pitcher-plant. 

Sphagnum. This occurred sparingly in depressions below the 
water level. 

Spathyema foetida (L.) Raf. (Symplocarpus foetidus Nutt.) 

1 Skunk Cabbage. 

Vagnera trifolia (L.) Morong. (Smilacina trifolia Dcsf.) Three¬ 
leaved Solomon’s Seal. 

Viola alsophila Greene. Marsh White Violet. 

Of these the Boehmeria, Dryopteris, Osmunda, Galium, Impatiens, 
Menyanthes, Gomarum, Sphagnum and Viola are found in the preced¬ 
ing list, and were common in the open marsh, the Gomarum and Meny¬ 
anthes in the water, the others somewhat above water level. Of the 
other species, the Garices except C. sterilis cephalantlia are species most 
often found in shaded swamps, often under tamaracks, and rarely in 
open bogs. The Coptis is a northern plant, found in rich woods in New 
England and in the Northern Peninsula and in swamps in the more 
southern part of its range. The Equisetum and Eriophorum are water- 
loving species, usually found in the open marsh, the latter often a con¬ 
spicuous species in the sedge mat, but able to persist after the Tamarack 
has invaded this, by keeping in the more open places. 

The Galium and Impatiens are plants very widely distributed in wet 
places, both in the open and under shade, the latter often being the 
only herb in the dense shade of very wet swamps. 

Leptorchis, Sarracenia and Vagnera are plants which are usually 
found in peat bogs, the Sarracenia as frequently, or more frequently 
in the open than in the shade, in fact, while it will endure partial shade 
for a time, as this becomes more dense it seems gradually to disappear. 
It is frequently found growing very abundantly in deep Sphagnum, but 
may grow to perfection in wet sedge marsh, as is shown by its occurrence 

in manv such marshes. 

*/ 

The Leptorchis, like other members of the Orchis family, is often 
found in the open marsh and sometimes grows perched as an epiphyte 
among the culms of Carex stricta Lam., several inches above the water. 

Vagnera trifolia is, like Coptis, a plant of northern range, growing 
generally in tamarack and cedar swamps, and while it is sometimes 
found growing in open places where Sphagnum is abundant, it is more 
frequent in the shade and seems to need it for its best development. 
The Violet mentioned, the Swamp White Violet, is common in shaded 


144 


MICHIGAN SURVEY, 1906. 


wet places of various types and will grow in shade where apparently 
little else is found, and where the soil is very wet at certain seasons. 

Of the other plants found here, the Sphagnum occupied the wet places, 
growing in the depressions between the roots of the trees and shrubs, 
and often in the standing water in these. More rarely it formed very 
small patches above the water level but it formed at the time these 
studies were made, no important part of the plant covering in this 
area. Spathyema foetida, the Skunk Cabbage, was much more abundant 
in some parts of the tamarack growth than in others, and often covered 
the ground entirely with its broad leaves where the soil was wet and the 
shade dense. It is an abundant plant in boggy and peaty soils which 
do not dry out, but seems to make a good growth in the beginning only 
under the shade of taller vegetation, but once established, it persists 
as long as the drainage conditions are not improved after the removal 
of the shade. It may establish itself at times in open springy places, 
where the conditions are favorable. 

After passing through the belt of Tamarack just described, a second 
sedge marsh is passed before reaching the original shore. This, how¬ 
ever, is gently sloping, and the surface is covered with Carex stricta as 
the most abundant plant and as this plant grows in tufts, the culms 
building up dense compact stools of peat, the associated plants are 
perched in part upon the dryer site thus afforded. The soil here is still 
very wet about the roots of the Car ex until late in the summer at least, 
but a number of plants found here occur in the slightly dryer types of 
marshes, and this would indicate that the slight slope gives some drain¬ 
age. Associated with the Carex stricta were the following species: 

Cornus stolonifera Miclix. Red Osier Dogwood. 

Dasiphora fruticosa (L.) Rydb. ( Potentilla fruticosa L.) Shrubby 
Cinquefoil. 

Rhus vernix L. Poison Sumach. 

Salix Bebbiana Sarg. (S. rostrata Rich.) Bebb’s Willow, and 
others. 

Rub us strigosus Michx. Wild Red Raspberry. 

Rosa Carolina L. Swamp Rose. 

These shrubs were few in number and scattered at various distances 
from the margin of the swamp. The herbs were the following: 

Dryopteris Thelypteris (L.) A. Gray. 

Boehmeria cylindrica (L.) Willd. 

Geum strictum Aiton. Avens. 

Solid ago Canadensis L. Canada Golden-rod. 

Verbena hastata L. Blue Vervain. 

Lycopus Americanus Muhl. (L. sinuatus Ell.) Cut-leaved Water 
Hoar hound. 

Thalictrum purpurascens L. Purplish Meadow-Rue. 

Asclcpias incarnata L. Swamp Milkweed. 

Aster puniceus L. Purple-stem Aster. 

Eupatorium purpurcum L. Joe-Pye Weed. 

Calamagrostis Canadensis (Mx.) Beauv. Blue. Joint. 

Iris versicolor L. Blue Flag. 

Asclcpias Syriaca L. (A. Cornuti Dec.) Common Milkweed. 

Potentilla Monspeliensis L., (P. Norvegica L.) Rough Cinquefoil. 


DAVIS ON PEAT. 


145 


The appearance of Calamagrostis Canadensis in this area marked a 
definitely lower water level during the growing season in the places 
where it was found than do the sedges. 

Returning to the sedge marsh on the lakeward side of the Tamaracks, 
and following around to the eastward the sedge was found to be replaced 
by Cat-tail, Typha, at the east end, except in limited areas, and there 
were indications that the latter was increasing the territory occupied 
by it, such as the presence of large numbers of young Typha plants 
among the sedge, and the close relationship of the position of the fern 
covered areas to that of the Typha. The probability that this was the 
case was strengthened by the fact that at Whitmore Lake within three 
years there has been a permanent elevation of the water level of 
more than a foot, and at Dead Lake a similar rise has occurred 
so that it is certain that one has taken place at Mud Lake, and those 
parts of the sedge mat which did not rise promptly with the water 
would become wetter than before, a condition which would favor the 
rapid increase of Typha in the vicinity of places in which it was al¬ 
ready established. Near the Tamarack, as this part of the marsh was 
crossed, were a few spots where the Cassandra, Chamaedaphne caly- 
culata (L.) Moeneh., had established itself in about the same relationship 
to the tamarack zone as the willows were on the south side, but it was not 
a marked constituent of the flora here. It Avas also noted that along the 
east end of the marsh there were numbers of young specimens of 
Tamarack growing with the Typha. 

The tamarack growth surrounded the entire lake with a nearly per¬ 
fect elliptical border, and as this was followed along around the east 
end to the north side, a very abrupt change took place in the character 
of the vegetation in the tamarack zone and the shrub zone immediately 
lakeward from it. The Tamarack became mixed with a considerable 
percentage of Spruce, and beneath these trees numerous shrubs occur 
which were not found on the south side, and the surface of the ground 
was covered with a heavy coating of Sphagnum moss. The shrub zone 
instead of being covered by species of Salix was occupied by Cassandra 
and other species of heaths, and extending lakeward was a dense growth 
of Sphagnum with scattering Cassandra plants, the Sphagnum growing 
sometimes in the water on the sedge mat, but not extending more than a 
few vards lakeward. The “islands” of fern in the sedge mat here had 
Cassandra and large amounts of Typha upon them than appeared in 
similar places on the south side. Considering these different associa¬ 
tions as before, the floras of the sedge mat and the open water were 
practically identical to those of the south side except that Eriopliorum 
gracile Kocli., Scheuchzeria palustris L. and Carex limosa L. were more 
conspicuous, growing at the same water level with the Carex fiUformis. 

The plants characteristic of the fern islands upon the south side, here 
made a more definite zone, which in places was well marked a sliort dis¬ 
tance lakeward of the shrub zone, which invaded it at intervals; the 
Sphagnum also often apparently found favorable conditions for growth 
here. 

The shrub zone was, as has already been stated, characterized by Cass¬ 
andra, but there were other interesting species, some of which give evi¬ 
dence that the marsh had not long been in possession of the shrubs. 
Such were: > 


i 


146 


MICHIGAN SURVEY, 1906. 


Carex filiformis L. 

Carex limosa L. 

Dulichium arundinaceum (L.) Britt. (D. spathaccum Pers.) 

Comarum palustre (L.) Marsh. 

Decodon verticillatus (L.) Ell. 

Eriophorum gracile Koch. 

Eriophorum polystacliyon L. 

which were usually missing where the Cassandra was dense. The 
shrubby plants in this outlying Cassandra zone were few, the Cass¬ 
andra constituting the great bulk of individuals, and being the most 
conspicuous as well, but frequently either mixed with it or in nearly pure 
growth, was found the Andromeda, Andromeda Polifolia L. (L.) Britt., 
while the cranberries Oxycoccus Oxycoccus (L.) McM. and Oxycoccus 
macrocarpus (Ait.) Pers. were noticeable upon the surface of the Sphag¬ 
num, sometimes on the lakeward side of the zone forming dense mats of 
their delicate vines, but they also were present among the Cassandra 
bushes. Here also were occasional specimens of Sarracenia and of various 
species of orchids, but none of these were important members of this asso¬ 
ciation. The zone was broken for short intervals here and there by de¬ 
pressions below the water level, and in and around these various plants 
of the lakeward zones persist. An indication of the future development 
of the plant growth was found in the numbers of small seedlings and 
young specimens of the Tamarack which were to be seen among the 
Cassandra plants and upon the Sphagnum. 

The Cassandra in much of this zone was nearly buried by the upward 
growth of the Sphagnum around its stems, which seemed to serve as 
supports for the moss. The main root system of the shrub and its 
underground propagating shoots were often two feet below the sur¬ 
face of the Sphagnum, and practically below the level of the ground 
water during most seasons, but as the Sphagnum surrounds the stems 
of the shrub, adventitious roots are developed, which, if they serve no 
other purpose, must increase the supply of air taken in by the plant. 
It is evident from this relationship of the Cassandra and the Sphagnum 
that the shrub must establish itself as soon as the moss or before it, 
since the root system is at the very bottom, and often below the moss 
formed peat, and a section of the bog here shows that immediately be¬ 
low the laver of shrub remains the characteristic structures of the sedge 
mat are to be easily identified. 

The width of this zone, including the fern association, was only two 
or three rods over a large part of its length, which was an eighth of a 
mile or more, and it was narrower than this in places. It was bounded 
on the shoreward side by the tamarack zone here composed of both 
Tamarack and Black Spruce, Picea hrevifolia Peck, which, as indicated 
above, is a very different formation from that found on the south side 
of the lake. Here the trees were very densely crowded in some places and 
scattered in others, but immediately along the border of the zone they 
were generally dense. 

At the east end was a portion of the zone with trees which are 10 to 
15 feet high, mostly Tamarack, with dead and dying Cassandra under 
them, the dead plants easily recognizable by their well-preserved stems. 



DAVIS ON PEAT. 


147 


A short distance shoreward (north) of this area was the beginning of 
a wide Sphagnum-Cassandra bog, which is described below. 

Continuing west in the tamarack zone, from the part just described, 
the trees were taller and more dense, and the following plants are found 
growing in their shade: 

T actinium corymbosum L. Swamp Blueberry. 

Ilicioides mucronata (L.) Britton. ( Nemopanthes fascicularis 
Raf.) Mountain Holly. 

Aroma nigra (Willd.) Britt. ( Pyrus arbutifolia melanocarpa 
Mx.) Chokeberry. 

Caylussacia resinosa (Ait.) T. & G. 

Oxycoccus Oxycoccus (L.) MacM. 

Oxycoccus macrocarpus (Ait.) Pers. 

Rhus remix L. 

Chamaedaphne calyculata (L.) Moench. (Seldom.) 

Hex verticil l at a (L.) A. Gray. Winterberry. 

The herbs include: 

Menyanthes trifoliata L. (In wet places.) 

Sphagnum. 

Cypripedium acaule Ait. Stemless Ladies’ Slipper. 

Vagnera trifolia (L.) Morong. 

Carex paucidora Lightfoot. Few-flowered sedge and other species. 

Dryopteris Thelypteris (L.) A. Gray. 

Woodwardia Virginica (L.) J. E. Smith. Virginia Chain-fern. 

Other sj>ecies occurred, but so sparsely in the shade that they need no 
mention here. An interesting species, common here, is Monotropa uni- 
Hora L., the Corpse plant or Indian Pipe, whose saprophytic habits ren¬ 
der it indifferent to shade. 

A study of the substratum of peat in this area showed that below the 
Sphagnum was a stratum of woody remains and the roots of the shrubs 
■and trees, which was about a foot thick, the lower parts of this being 
poorly decomposed and easily recognizable as shrub remains. There 
had apparently been some sinking of these upper layers of peat, for the 
bottom of the woody zone was, so far as could be determined, several 
inches below the level at which shrubs are recognizable on the lakeward 
^one, while the water level stands at about the same distance from the 
surface at any given time. Below the stratum of woody remains, at a 
depth of less than two feet, the top of the sedge stratum was reached, 
containing the characteristic and well-preserved parts of the rootstocks 
of Carex and the other plants of the sedge mat. 

Following along to the west in the tamarack zone or along the marsh, 
about half way down the north side of the lake, the Cassandra zone 
was abruptly displayed by Typlia. The Tamarack persisted in a nar¬ 
row zone, but the Typlia passed through and behind it, Avhile from 50 
to 100 feet lakeward in the Typlia marsh were numerous young Tam¬ 
aracks a few feet high. Shoreward of the Tamarack was a rather dense 
growth of Willows, Poplars, much Rhus vernix L., Rubus stidgosus Mx. 
and a few young Elms, Ulmus Americana L., White Ashes, Fraxinus 
Americana L., and Red Maples, Acer rubum L. The Sphagnum became 
very rare, as did the low shrubs, which, until this place was reached, 


148 


MICHIGAN SURVEY, 1906. 


had been very abundant, while Vaccinium corymhosum L., the Blueberry y 
which had been a characteristic plant, disappeared entirely. There 
were numerous hollows, in which water stood, and the shrubs and 
trees were all on the low hummocks which covered the ground between 
these. The shade of the woody plants was so dense that there were few 
herbs to be found, and the few that were present were unimportant as 
constituents of the association. The numerous dead tamarack poles, 
and the peculiarly sharp transition from one type of vegetation to the 
other, as w r ell as the peculiar association of plants which existed, all 
pointed to some sudden and violent change of conditions, by which not 
only was the old vegetation entirely destroyed, but the soil and soil 
water relations so changed that the area could not be restocked from 
the unaffected part to the east, before the plants from higher ground 
came in and occupied the vacant space. The indications all pointed to 
severe fire during some dry period at no very remote date, as the agency 
most likely to have caused such a wholesale change and the fire marks 
on the tamarack stumps were additional evidence in this direction. The 
fire not only killed and removed the vegetation but also burned off the 
loose layers of vegetable debris from the top of the peat, and improved 
its mechanical and chemical composition and thus fitted it for the types 
of plants which now occupy it, but this very removal of the surface 
material brought the surface so much nearer the water level that the 
Typha was able to invade the area, and if any prolonged period of high 
water occurs the new association of plants will be destroyed and the 
former will then be able to close in again. This was already indicated 
by the presence, in the Typha marsh on the lakeward side, of young 
Tamaracks and patches of Cassandra, which were not losing ground in 
this situation. 

At the west end of the lake was a sedge bog, apparently a floating 
mat, with Carex filiformis L. as the dominant plant. Shoreward were 
abundant Typha plants and many Tamaracks from 5 to 10 feet high 
were scattered over it. 

Returning to the eastward, beyond the path of the old fire, and cross¬ 
ing the bog towards the north, an open Cassandra-Sphagnum tract was 
found. Here the principal plants were the shrubs, Cassandra and 
Andromeda, but Tamaracks and Black Spruces were scattered over the 
bog in considerable and increasing numbers, as was shown by the 
numerous young individuals. In addition to the trees, there were sev¬ 
eral species of tall shrubs which formed a dense growth around the 
borders of the Cassandra and were spreading rapidly into and over it, 
as could be seen in many places where the lower shrubs were already 
dead under the taller ones. The plants growing here were: 

I actinium corymhosum L. Swamp Blueberry. 

Vaccinium Canadense Richards. Canada Blueberry. 

Vaccinium Penns yluanicum Lam. Dwarf Blueberry. 

Andromeda Polifolia L. Andromeda. 

Kalmia glauca Ait. Pale Laurel. (Rare.) 

Gaylussacia resinosa (Ait.) T. & G. 

Ilicioides mucronata (L.) Britton. (Border.) 

Aronia nigra (Willd.) Britton. (Border.) 

Oxycoccus Oxycoccus (L.) McM. 


DAVIS ON PEAT. 


149 


Oxycoccus macrocarpus (Ait.) Pers. 

Populus tremuloides Michx. American Aspen. 

Picea hrevifolia Peck. 

Larix laricina (DuRoi) Kocli. 

Carex pauciflora Lightfoot. 

Carcx oligosperma Michx. Few-seeded Sedge. 

Eriophorum vaginatum L. Sheathed Cotton-grass. 

Eriophorum Virginicum L. Virginia Cotton-grass. 

Scheuchzeria palustris L. 

Sarracenia purpurea L. 

Monotropa uniflora L. 

Sphagnum. 

Polytrichum. 

Charred stumps and other remains of trees, mostly Tamaracks, showed 
that here again fire had been instrumental in removing the older vegeta¬ 
tion, and in bringing about a renewal of former conditions by letting 
in the light and lowering the level of the ground. 

Here, as in the Sphagnum-Cassandra zone, the Sphagnum nearly 
buried the shrubs Cassandra and Andromeda, but where the former was 
very dense, the moss does not persist, and the same was true of it under 
the young Spruces, where it was entirely absent in many cases but went 
on growing upward around the circle formed by the branches of the 
trees until it built up for 18 or 20 inches with a steep slope on the side 
under the trees, where the surface was often more than a foot lower 
than that outside. These banks of Sphagnum were commonly covered 
with the vines of the Cranberries and with Andromeda, and less fre¬ 
quently Sarraccnia, Cypripedmm acaule Ait., Monotropa uniflora L., 
and young Spruces grew upon them. The water level, in early summer, 
was above the level of Ihe lowest parts of this area, above that in which 
the roots of the shrubs lie, but in dry times it gets considerably lower. 
At this place the indications were that the Sphagnum has built up as 
high as it can, when it has reached a height of about two feet above 
the ground water level, and in a few cases it was found that upon the 
top of partially dead mounds of Sphagnum, another moss, Polytrichum, 
had established itself. This is a dry ground type and seemed to thrive 
in this place, as it does upon the surface of more thoroughly decomposed 
peat. The fate of this Cassandra-Sphagnum bog was plainly to be read 
by a brief study of the area which lay between it and the higher ground 
to the north, for in passing across this, the margin around the bog 
was covered with dense growth of taller shrubs, Vaccinium corymhosum 
L., Aronia nigra (Willd.) Britt., Ilicioides mucronata (L.) Britt, and 
Ilex verticillata (L.) A. Gray. Of these, the Aronia nigra (Willd.) Britt., 
the Chokeberrv, is particularly aggressive in occupying new ground or 
that occupied by lower plants, for it sends out long underground stems, 
which in turn develop vertical leafy branches, which grow up through . 
the moss and Cassandra thickets, and, overtopping them, soon destroy 
them. In parts of the area to the north of the Cassandra bog, there 
were remnants of an old Tamarack growth under which were tall 
mature shrubs of most of the species mentioned above, forming a suf¬ 
ficiently dense shade to keep most of the ground bare except for mosses 
and some few small herbs. Among the Tamaracks there were also good 
20 


150 


MICHIGAN SURVEY, 1906. 


sized trees of Betula lutea Michx. f., and less frequently Acer rubtum L. 
and I*o pul us tremuloides Michx. In the lighter and more open places 
here, the following herbaceous plants were found: 

Aralia nudicaulis L. Wild Sarsaparilla. 

Cypripedium acaule Ait. 

Unifolium Canadense (Desf.) Greene. 

Woodwardia Virginica (L.) J. E. S. 

Sphagnum. (In lowest wet places, in best light.) 

Carex canescens L. Silvery Sedge. 

Carex trispenna Dewey. Three-seeded Sedge. 

Pteridium aquilinum (L.) Kuhn. ( Pteris aquilina L.) Common 
Brake. 

Coptis trifolia (L.) Salisb. 

In addition to the shrubs, young specimens of Betula lutea Michx f. 
and Acer rubrum L. were common. 

The peat here was of a granular structure near the surface, and is 
reddish brown in color. In early summer, the water stands near or at 
the surface of the low places and unless the season is very dry, does not 
get very low at any time. The top layers of peat were composed of the 
remains of branches, and other woody parts of trees and shrubs, with 
well-marked layers of leaf remains intermixed, extending down a foot 
or more from the surface. This layer was compact, and filled for sev¬ 
eral inches with the living roots of the trees and was coarsely granular 
in structure. 

The peat in the Cassandra zone was much less granular, was softer and 
wetter, and was made up of the easily identified remains of Sphagnum 
for about a foot or a foot and one-half from the lowest places upon 
the surface. Below this was a thin stratum of shrub remains, char¬ 
acterized by well-preserved branches and stems of the shrubs, and under 
this within two feet of the- surface, where the tests were made, the 
sedge turf was reached and abundant root-stocks and other parts of 
the Carex and accompanying plants were present and were brought to 
the surface. 

Bordering upon this region of mature Tamaracks and covering a 
large part of the shoreward residue of the swamp, was a very dense 
growth of Poplars and Willows, interrupted frequently by shallow 
pools of small extent. These pools were bordered by Typha, various 
species of Carex and often by the low growing shrub Willows. Every¬ 
where through this area were found the scorched remains of Tamaracks 
and Spruces, in many places the stumps with the roots almost entirely 
exposed, showing a considerable lowering of the surface level of the 
peat. It was evident that here again fire had changed the conditions, 
modified the structure of the soil and lowered its surface, and the pres¬ 
ent plant growth was of very recent origin. The presence of young 
Tamaracks under the Poplars was an indication that a new cycie has 
begun, which may eventually restore the Tamarack to its dominant posi¬ 
tion. 

« 

At the outer edge of the north side was a well-marked fosse, or mar¬ 
ginal ditch—an open space usually covered with water from 1 to 2 feet 

deep, and supporting a dense growth of Carex riparia W. Curtis and 
Typlia. 


DAVIS ON PEAT. 


151 


This sort of depression is nearly always present about the margins 
of peat deposits of this type, often extending entirely around them, and 
is generally wholly or partly filled with water, at least in wet seasons, 
and has an association of plants similar to that found here, the list of 
which might be considerably extended. 

Similar phenomena have been discussed by McMillan, 1 who attributes 
the formation of Sphagnum atolls to “a season of gradual recession of 
the waters, followed by a season of comparatively rapid increase in area 
and level." Atkinson 2 attributes this ditch to the rapid and luxuriant 
growth of the original plants which establish themselves three or four 
meters from the shore and build up a deposit, from which the filling 
begins to work lakeward, “shutting off the shallower water near the 
shore from the deeper water of the pond.” 

In the numerous examples of this part of swamps and bogs of Michi¬ 
gan examined by the writer, it has seemed that the efficient cause in 
their production was the fluctuation of the water level through rather 
brief intervals and the constant recurrence of such fluctuations. These, 
as has already been pointed out, are attendant upon the variations in 
the rainfall, and the water level in the lakes, and depressions, may vary 
one, two, or more, feet every few years, and may remain at the low water 
stage for several years in succession, as has been shown is the case at 
Whitmore Lake, where the low water period was sufficiently long to en¬ 
able young Red Cedar (Juniperus Virginiana L.) trees to establish 
themselves and reach a height of several feet on the abandoned lake 
bottom, before the water rose again. A similar drop in the water level 
took place at Rock and Bass Lakes in Montcalm county, the water being 
over two feet lower in 1894-1897 than in 1904. In like manner many 

nJ 

shallow depressions which have been under cultivation during dry 
periods are, at the present writing, ponds. It is also a matter of ob¬ 
servation that, during dry times, the water does disappear from these 
marginal ditches for long periods during the summer and fall, the 
bottoms becoming quite dry and this has the effect of destroying much 
of the hydrophytic vegetation which has established itself and also of 
thoroughly decomposing and disintegrating the organic matter which, 
has accumulated during periods of high water, thus lowering the sur¬ 
face below that of the area directly above the zone of permanent water, 
which, being covered by a thicker layer of vegetable debris, is kept wet 
by the upward capillary movement of the water from below its surface. 

Besides Mud Lake, a considerable number of other lakes were visited 
in which the sedge, Typlia or similar floating mats were present, 
and in each of these practically the same plants were found. An in¬ 
teresting variant from the mat described above is that at Frain’s Lakes, 
in Secs. 9 and 10, Superior township, Washtenaw county (Tp. 2 S., R. 
7 E.) at a small pond on secton 11, Northfield township, Washtenaw 
county (T. 1 S., R. G E.), at Long’s Lake, Davison township, Genesee 
county (T. 7 N., R. S E.), and in parts of other lakes visited, in which 
the plant making the advance from the margin was Decodon, verticil- 
laUis (L.) Ell., mentioned as occurring at Mud Lake rather rarely. This 

made dense borders around the entire body of water on the two last 

«/ 

lakes cited above, and was present upon the entire front of the advanc- 


3 McMillan, C., Geol. & Nat. Hist. Surv. of Minn. Bull. 9, Tart 1, p. 13. Minneapolis, 1894. 

2 Atkinson, G. F., Op. cit. p. 389. 





152 


MICHIGAN SURVEY, 1906. 


ing mat at Frain’s Lakes. This plant is capable, of forming masses of 
stems which bend over and root at the tips, at the same time making 
rather dense shade. The stools which they form are slightly higher than 
the water surface and such plants as can endure the shade and water, 
associated with the Decodon by establishing themselves upon these 
stools, and following in behind the advance of the Decodon, the sedges or 
Typha occupy the surface of the deposit. The Decodon stems die down 
each year and the advance of the plants at Train's Lakes could be dem¬ 
onstrated by the existence of a number of concentric lines in the sedge 
mat, parallel to the present shore, in which there were a few plants 
of Decodon, less thrifty and smaller than those at the present water 
margin. 1 At Frain’s Lakes the filling was in the middle of a long nar¬ 
row depression, the mat having apparently built out from the north 
shore towards the south for a portion of the length of the valley and 
the rest of it, except at the east end of the east lake, is practically with¬ 
out any peat. The filled portion of the valley is nearly a fourth of 
a mile long and is, much of it, still covered by floating mat, through 
the lowest part of which is a channel connecting the two lakes. 

Lakes with sedge mats are illustrated by the south shore of Half Moon 
Lake, in Gratiot county, by numerous examples in Livingston, Wash¬ 
tenaw, Isabella, Oakland and Ingham counties. In Roscommon and 
Wexford counties the localities visited were depressions which had 
been completely closed in, and, while it was apparent that the same 
plants as those noted in Mud Lake were present and had been actively 
engaged in the process of filling, the advanced stage of the deposits made 
the exact steps of the process not so apparent. 

The Water Plants and Sedge in Relation to the Peat. 

If the sedge or Typha mat, as long as it is afloat, does not support 
any considerable number of other species of plants than those making 
it, and these are superficial upon the surface of the mat, and if the peat 
is gradually built up under the mat until this no longer floats, it is 
evident that the sedge must be considered as the chief agent in filling 
in the space between the under surface of the mat and the top of what¬ 
ever deposit the water plants and other agencies have formed below, un¬ 
less a circulation of water below the mat brings in and deposits dbbris 
formed outside its edge. This hardly seems probable to the writer, but 
his investigation has not gone so far as to lead to a final conclusion. 
Until such a conclusion is arrived at the alternative that the com¬ 
pletion of the filling of the area under the mat is due in part to thick¬ 
ening of the mat, and, in part, to material which falls from the under 
side of it while it is being thickened by the growth of sedge above, must 
be accepted. 

The final stage in the filling of deep depressions is reached when the 
mat closes over the water surface entirely, and the water below is so 
filled with peat that the entire* surface becomes firm. After this the 
surface is built up above the water level by succeeding plant societies 
which are represented in the zones at Mud Lake. 

After the water of the entire lake has been covered it is usuallv diflfi- 

Is 

1 For a further discussion of the importance of this plant in peat formation, see the account in 
Part II. of this Report. 





DAVIS ON PEAT. 


153 


cult to determine whether the method here described has been that by 
which it was accomplished or not, but if soundings sliow N the basin to 
be a deep one, a vertical section will usually give proof that the sedge 
has been a chief factor in the later stages of lake destruction. 

Following the time when sedges or other advancing plants have closed 
in over the surface of the open water of a lake or pond, however, the 
mat slowly thickens, as has already been pointed out, both by the 
building up of the surface, through the accumulation of vegetable ddbris 
and by the sinking of the mat, partly through the replacement of air 
and other gases held in the plant tissues by the water, water-logging, 
but more because of the increased load upon the surface, after the 
heavier tree associations become established. This sinking is, however, 
a slow process, and only goes so far as is necessary to establish equili¬ 
brium, i. e., until the mat is built up sufficiently to sustain the weight 
upon it. The thickness of this mat, even at its maximum development, 
is small relative to the entire depth of the deposit, rarely more than 3 
or 4 feet, and in but a single case in the series examined, showing as 
much as G feet of material, which could be considered true mat, before 
the fluid, or semi-fluid, structureless peat below the mat was reached. 

In considering the phenomenon of the thickening of the mat in this 
type of peat deposits, it is probable that in some cases there has been 
a gradual and permanent elevation of the water level, amounting to a 
foot or more, due to interference with the drainage from the basin, as 
the mat covers more and more of the water contained within it, and a 
lessened evaporation from the surface as the area of open water becomes 
more and more contracted by the growth of the mat. This interference 
with the drainage can readily be seen in most lakes with outlets, which 
are partly covered by sedge mats, but the difficulties in the way of 
securing absolute confirmation of the effects of such interference on the 
water-level, are such that none can be presented here. 

Another factor to be considered in accounting for the thickening of 
these structures is the periodic elevation of the water surface due to 
cycles of increased rainfall, during which, for longer or shorter times 
the ground water level is raised, together with that of lakes, as has 
been pointed out in another place. While the floating mat undoubtedly 
rises with the water level to a considerable extent, there are parts of 
it which do not respond quickly to changes of level, and upon these the 
water is increased in depth in times of high water, so that water plants 
may establish themselves, and the plants already present may grow 
above the' level at which they did before the rise occurred, thus increas¬ 
ing the thickness of the mat by adding to its upper layers new strata 
of rootstocks and roots. 

It seems to be generally true, however, that whether the water has 
risen over the mat, or the mat has sunk below the water, the changes 
have gone on very slowly, often at about the rate at which the surface 
of the mat has been built up, since sections of these thickened surface 
structures show that during a large part of their history the plants 
forming them have been those which thrive either at or just below the 
water level. 

The fact that many of the apparently filled lakes of Michigan have 
been covered by such thickened mats as those described above, rather 
than filled, has been discovered, to their great cost and embarrassment, 


154 


MICHIGAN SURVEY, 1906. 


by the railroads of the state and the engineers in charge of their con¬ 
struction and maintenance. The level, comparatively open surface of 
such bogs, as well as the apparent stability of the substratum offer 
special attractions for laying out railroad lines, which have often been 
irresistible to locating engineers. Apparently the errors have come from 
false estimates of the solidity and stability of the peat, gained by the 
use of inefficient sounding tools in the preliminary tests made to esti¬ 
mate the depth and stability of the substratum, for these tools will give 
samples which are very deceptive, since they generally show solid peat 
from all depths if they pass through a few feet of it, near the top of 
a deposit, bringing nothing from the fluid mass below. 

This relatively thin covering stratum, usually only 3 or 4 feet thick, 
for a time after the line has been constructed, has borne the additional 
weight of grade and track and has endured the traffic, but sooner or 
later the track has sunk under an unusual load imposed upon it, by 
the passage of a heavily loaded train, or has persistently moved from 
its proper alignment under stress of continued use, because of the un¬ 
stability of the peat substratum. Such bogs have given much trouble 
along the lines of the Pere Marquette, Ann Arbor, Michigan Central, 
Grand Trunk and other railroads in various places, and in the Northern 
Peninsula are still causing more or less anxiety along the lines of some 
of the more recently built roads. 

A case notable in the annals of railroad engineering is described by 
Waterbury, 1 from Avhose paper the accompanying facts and Figs. 5 to 8 
have been taken. 

The road was originally built with a single track, and a large amount 
of timber was used to form a foundation for the roadbed, which was 
built above it. This is shown in Fig. 5. For a considerable time this 


Fig. 5. 


Cross section showing original construction of Grand Trunk railway upon floating mat of 

bog near Lansing. (Waterbury). 



a 


single track was sufficient for the needs of the road, and little diffi¬ 
culty was experienced from the instability of the substratum until 1902, 
the track was doubled. In the process of this work “the dirt, which 
was dumped by the side of the existing embankment, gradually sunk 

1 Waterbury, L. E., Haslett Park sink-hole on the Grand Trunk Railway. The Michigan Engineer 














































DAVIS ON PEAT. 


155 


out of sight, leaving a pond of water, at the same time forcing the track 
and right-of-way fences out of line.” (Fig. 6.) 




The displacement of the fence was 38 feet from its original position, 
and of the track more than l^/o feet. The weight of the material for 
widening the old embankment broke the mat, carried down with it a 
portion of the old filling as well as the peat below it, so that the track 
sank whenever trains passed, sometimes a half foot, and this would 
have to be raised by filling before the track could be used again. In 
filling the opening permanently about 30,000 cubic yards of material 
were used before the track stopped sinking. (Fig. 7.) 



I 

Fig. 7. Cross section, showing the displacement of the original embankment and of the floating mat, 

by filling for the double track. 


In this figure also is shown the peculiar rising up of the mat, which 
amounted to at least 6 feet, caused by the displacement of water and 
soft peat below it, by the material used for filling. 







































































156 


MICHIGAN SURVEY, 1906. 



Fig, 8. Profile of a section of the bog along the line of the track. Figures on the right, elevation 

above the sea level. 


In Fig. 8 is shown a profile of a section of the bog along the line of 
the track, the greatest depth being about 28 feet. In another, larger 
bog, on the line of the same railway, and less than 6 miles from the 
one described, there were used more than 60,000 cubic yards of filling 
in making the changes from single to double track. This depression 
was 55 feet deep. 

The bog at Haslett Park was visited by the writer in June, 1905, and 
while considerable change had taken place in the vicinity of the sink¬ 
hole as described above, the elevated portions of the mat were still 4 feet 
above the water level, the shrinkage being in part due, in all probability, 
to the drying of the peat and to a certain extent, also, to changes of 
water level. 

The surface of the bog was covered by the remnants of a forest of 
broad-leaved trees, mixed, in places, with Lanx laricina (Du Roi) Koch, 
Tamarack, especially near the place where the sinking of the track had 
occurred. The following broad-leaved species of trees and shrubs were 
noted here: 

TJInins Americana L. White Elm. 

Quercus macrocarpa Michx. Bur Oak. 

Quercus platanoides (Lam.) Sudw. Swamp White Oak. 

Quercus rubra L. Red Oak. 

Acer rubrum L. Red Maple. 

% 

and a few other species forming a partly cleared zone around the shore¬ 
ward margin. In a somewhat more open area extending from the edge 
of this to the sink-hole were scattered young specimens of some of these 
species, together with larger and more mature ones of: 

Lanx laricina (Du Roi) Koch. Tamarack. 

Populus tremuloides Michx. Common Aspen or Poplar. 

Salix nigra Marsh. Black Willow. 

Betula lutea Michx. Yellow Birch. 

Fraxinus nigra Marsh. Black Ash. 











































































































































































































DAVIS ON PEAT. 


157 


As undergrowth appeared the shrubs: 

Corylus Americana Walt. Hazelnut. 

Elms Vernix L. Poison Sumach. 

Bctula pumila L. Dwarf Birch. 

Aronia nigra (Willd.) Britt. Choke-berry. 

Rosa Carolina L. Swamp Wild Rose. 

Sphagnum was found covering small areas north of the right of way 
of the railroad and, in spots along the recently made cut through the 
raised portion of the mat. Sphagnum peat formed hummocks from 1 
to 3 feet high above the general surface. A section through one of these 
gave the following results: 

Living Sphagnum . 6 in. 

Light colored, poorly decomposed moss peat 

with remains of shrubs and other plants. ... 2 ft. 

Light colored moss peat with abundant root¬ 
stocks of Dryopteris Tlwlypteris (L.) A. 


Gray. Marsh Shield-fern. 3 in. 

Below which was: 

Coarse brown peat with tree roots and stumps 2 ft. 0 in. 

Shrub remains . 2 in. 

Finer and darker peat with sedge remains 
abundant. 2 ft. 


In a section through the most, elevated part of the upturned mat, where 
there was no Sphagnum, measured from the top to a distance of a foot 
below the water level, the following strata could easily be made out: 


Surface litter . 0 in. 

Brown, coarse, poorly decomposed peat filled 

with tree roots and occasionally stumps... 2 ft. 3 in. 

Shrub remains . 3 in. 

Mare compact darker peat with rootstocks of 

the Marsh Sliield-fern abundant. 2 in. 

Fine grained, dark colored peat, without re¬ 
mains of woody plants, but quantities of 
sedge and Bulrush fragments. 2 ft. G in. 


In some parts of the cut, layers of charcoal, the evidence of former 
fires were noted from 1 to 2 feet below the surface of the pushed up por¬ 
tion of the bog. The thin strata between the shrub and sedge remains, 
which had masses of the characteristic and easily identified underground 
stems of Dryopteris Thelypteris, the Marsh Shield-fern, were not always 
present, but were found in several places in the cut. 

Below the stratum of sedge remains it was not easy to determine the 
remaining strata because of the depth of water present, but the peat 
was very dark colored and had little structure, although fragments of 
sedge leaves and rhizomes were occasionally found. 

In a mass of this sort of material, probably from a lower level than any 
of the sections above, seen on the south side of the electric railway and 
at the west end of the uplift, the fine grained, structureless character 
was very noticeable, yet, even in this, fragments of the characteristic 
21 










158 


MICHIGAN SURVEY, 1906. 


sedge remains could readily be made out, although not so abundant in 
it as in the material in the other sections. 

In a second uplift, to the east of the one described, and on the south 
side of the Grand Trunk Railway, the elevation was a little over 4A/% 
feet above the water with great cracks a foot or more wide, radiating 
from it, to the south. A section of this uplift gave the following strata 
from the top down: 

Litter and living plants. 4 in. 

Coarse peat with tree roots. 2 ft. 6 in. 

Shrub remains . G in. 

Fern rootstocks. 2-4 in. 

Sedge rootstocks, leaves, etc.1 ft. to 1 ft. 4 in. 

Water-level, below which no examination was made. 

From these sections it is evident that in this instance the foundation 
of the mat was built up, as has been already shown, by the water-loving 
sedges, but that the upper portions had been formed largely by the 
woody plants, of which the trees, with their attendant plant associates, 
were the most important. 

In these sections it will also be noted that the orderly succession of 
types, described as occurring on the surface of many similar localities, 
is here clearly recorded in the superposed layers of the mat which is 
the substratum of a mature swamp forest. 

Succession of Plants Upon the Peat After the Grounding 

of the Sedge Mat. 

There are certain types of plants which apparently are always ready 
to reach out from the dryer places, and establish themselves in the 
open areas which are offered by the surface of a peat deposit formed 
as indicated above, and whenever a change in the elevation of the sur¬ 
face takes place in any way they are quick to take advantage of it. 
Chief among the plants to appear upon the sedge mat, even before the 
surface has been raised above the water level are several species of 
aquatic and semi-aquatic mosses, the most noticeable ones belonging 
to the genus Hypnum, or more rarely, Sphagnum. On the first eleva¬ 
tions, an inch or two above the surface of the water, the plants which 
appear first are principally herbs,.the most conspicuous and generally 
distributed species being the Marsh Shield-fern, Dryopteris Thelypteris, 
which is usually accompanied by a considerable number of plants found 
with it at Mud Lake, all of which are more or less able to add to the 
deposit upon which they grow and build up the surface, when they, in 
turn, are displaced by more aggressive types. 

The Dryopteris and its accompanying species not infrequently form 
well-marked zones where conditions are favorable, but they are more 
often found in patches, in places where drift material has lodged at 
high water, or in scattered small groups, or on hummocks formed by 
the stools of sedge, stems of Typha, etc. 

The fern association was not always a noticeable element of the 
flora of the sedge mat, but as the same may be said of all other types 
as well, this is not significant. 







DAVIS ON PEAT. 


159 


Following the fern, the Sphagnum moss is often found encroaching 
upon the sedge, usually starting upon the fern “islands,” so that where 
the fern association is well represented, all stages of its introduction 
are to be found. Sphagnum grows with erect, more or less branching 
stems, which crowd so closely together that they form a dense cover 
to the surface of the parts of the bog upon which they grow, the upper 
parts of the plant continuing to grow after the lower part is dead, 
and in favorable places they may build the surface up to a height of 
two feet or more, especially where they are associated with shrubs. 
Some species persist and even thrive when the mat is flooded by water. 
These mosses are so much more vigorous in their growth than the 
Hypnums that they are more easily seen and more generally known, 
and to them is frequently attributed the formation of all peat, in fact 
they are known as the “peat mosses.” The Sphagnums are not inva¬ 
riably found in Michigan in the types of swamps under discussion, in 
fact they rather seldom occur in places where they might be expected, 
less than 30 per cent of the number of lakes, marshes and bogs visited 
on the course of this investigation, having any Sphagnum , even when 
other bog plants were present. The order of the appearance of the 
Sphagnum is apparently invariable, so far, at least, as the species which 
build the abundant surface coverings of the marshes and bogs to which 
they give the name are concerned, for not only does it exist in the south, 
as illustrated by the Mud Lake and Dead Lake developments, but in 
Gratiot county at Half Moon Lake, Montcalm county at the west end 
of Bass Lake near Vestaburg, in Wexford county, in the bog near 
Hobart Station, and in several localities in Roscommon county, espe¬ 
cially near Boyce Lake in Tp. 2L N., R. 3 and 4 W., it is the invariable 
order of succession. 

The same relationship has been noted by the writer and is shown by 
Whitford 1 to exist in the northern part of the state on the islands in Lake 
Michigan and is indicated less clearly by Coulter 2 for the same region. 

* At about the same time, or level, at which these mosses appear, some¬ 
times with them, sometimes by themselves, before them, certain shrubs, 
and a few species of trees make their advent in sufficient numbers to 
give character to the vegetation. 

While these may appear often as scattered individuals upon the 
sedge mat or with the ferns, they are there simply stragglers, but at 
the level slightly higher than that at which the ferns are most promi¬ 
nent, Willows of a number of species, a variety of heatlr plants, the 
Dwarf Birch, and other shrubs, such as Myrica Gale L., the Sweet Gale, 
and Loniccra ohlongifolia (Goldie) Hook, the Swamp Honeysuckle, be¬ 
come common, make good growth and often cover the surface com¬ 
pletely. The tree species which first establishes itself is the Tamarack, 
which often appears as isolated individuals on the open bog in advance 
of other woody species, but in denser growth is apparently restricted 
to the same level as the shrubs or a slightly higher one. 

1 Wh’tford, H. N. Bot. Gaz. 31. 1902, pp. 313-314. 

2 Co”lter, S. M., An Ecological Comparison of Some Typical Swamp Areas. Rept. Mo. Bot. Gaxd. 
15, 1904, p. 46. 


I 



160 


MICHIGAN SURVEY, 1906. 


Some Ecological Factors Which Control This Succession. 

The plants of this association have given students of the peat bog 
flora much difficulty, and writers upon plant ecology have made many 
attempts to explain their peculiarities of structure, and to reconcile 
these to their habitat, but no wholly acceptable theories have yet been 
advanced. 

The shrubs which make their appearance at the water level indicated 
above, have especially well-marked adaptations to reduce the transpira¬ 
tion of water, that is, they are xerophytes 1 or drought plants while they 
live under conditions where there is a large excess of water, apparently 
always available. Some of the adaptations found in these shrubs are thick¬ 
ened leaves, thick, dense cuticle, glaucous (or waxy), or, less frequently 
scurfy, woolly, or hairy, and, in case of Gaylussacia , resinous, covering 
for the leaves, especially on the under side and for the young twigs. The 
leaves are elongated or narrowly linear in form, often rolled, i. e., re¬ 
duced in size, or in the case of the conifers, short needle or awl-shaped, 
or reduced to scales. 

Schimper 2 attributes this peculiarity to impeded absorption of water 
l>y the roots, caused by the presence of humus acids in the peat. Liv¬ 
ingston, 3 however, has pointed out that “Bog waters do not have an 
appreciably higher concentration of dissolved substances than do the 
streams and lakes of the same region,” and it is therefore evident that 
any effects produced by the humus acids must be chemical, if they are 
present at all, because the osmotic effect of bog water is that of ground 
water generallv, and will be as readilv absorbed by roots. 

Whitford 4 adds to the above the factor of “insufficient aeration of 
the soil, which prevents a healthy growth of the root system of land 
plants, and also bars the presence of nitrifying bacteria.” Adding that 
“These probably bring about xerophytic structures of the plants so 
commonly seen in hydrophytic habitats.” Cowles 5 states that N. H. Nillson 
attributes the differences between the hydrophytic and xerophytic swamps 
to differences in food supply. It has also been suggested that the dif¬ 
ferences in temperature between the water about the roots and that of 
the air around the foliage of the plants in the open swamps and bogs, 
produces a tendency to excessive transpiration accompanied by slow 
absorption from the soil, the roots’ activity being reduced while that of 
the leaves is accelerated, thus producing a need of protection against 
the loss of water which causes the xerophytic structure mentioned. 

A comparative study of the plants of this shrub society and its 
habitat has made the following interesting facts apparent: 

1st. The area of swamps upon which these plants become dominant 
is fixed so that it no longer rises and falls with fluctuations of the water 
level of the lake, hence the water rises and falls in the peat as it does 
in other soils, often as much as 15 feet in peat deposits around ponds. 

2nd. During periods of minimum rainfall, the water level may fall 
sufficiently to leave the Sphagnum and the upper layers of the peat 
very dry, sufficiently so that they will readily burn, as is shown by the 

1 Schimper, Op. cit. pp. 3-17. 

2 Schimper, A. F. W., Op. cit., pp. 4 and 111. 

3 Livingston, B. E., Bot. Gaz. 37 : 383-385, May 1904. 

4 Whitford, H. N., Op. cit. p. 314, 315. 

6 Cowles, Loc. cit. pp. 75-76. 




DAVIS ON PEAT. 


161 




extensive areas burned over at Mud Lake and in a number of other 
localities visited, in which from one to three feet of peat have been 
burned off. These dry periods may last for several years and during 
their continuance the habitat is actually, not potentially, very dry. 

3rd. From peat, unless thoroughly decomposed, because of its 
mechanical structure, it is difficult to extract water by any means ex¬ 
cept heat, the water being held in the cell and vessel cavities of the 
partially disintegrated vegetable matter so firmly that the strongest 
pressure will not force it out, beyond a certain limited amount, and 
centrifugal force is equally ineffective. 

These facts have been established by experiments in attempting to 
prepare peat for fuel without heat, and make it apparent that plants 
growing with their, roots in peat in which the water content does not 
approach saturation will have difficulty in extracting sufficient for their 
needs. In other words, peat above the water level is structurally a very 
dry soil. Moreover, when it is once thoroughty dry, or even only air 
dry, peat does not readily absorb more than a small per cent of water, 
and a block of the material may be exposed for days to water without 
becoming Avet through, because certain soluble matters in it become col¬ 
loidal in drying and form a nearly insoluble coating in the outer layers. 
This property tends to prolong the period of drought in a bog that has 
been dried out. 

Direct experiment with plants has demonstrated the soundness of 
these conclusions, for as long ago as 1875, according to Warrington, 1 
Heinrich 2 reported that various crop plants required much more water 
when grown in peat to prevent wilting than in other kinds of soils, and 
that in the case of the potato the amount of water required was 41.4 
per cent of the weight of moist, or 70.8 per cent of dry peat. This 
amount is very much greater than that required in any other soil, as 
is shown by the following table: 

Parts of Water per 100 of Dry Soil. 


Absorbed from 

Type of soil. When plants wilted. moist air. 

Coarse sandy soil . 1.5 1.15 

Sandy garden soil. 4.6 3.00 

Fine humus sand. !... 6.2 3.98 

Sandy loam . 7.8 5.74 

Calcareous soil . 9.8 5.20 

Peat . 49.7 42.30 


In experimenting with crops on peaty lands, it has been demonstrated 
that the peat must contain more than 60 per cent of its weight of water 
to yield productive crops. 3 If these results are correctly reported, it 
appears that peat may appear very wet, and yet contain no water 
which is available for plants growing in it, so that those which habitu¬ 
ally grow at levels of peat bogs where the surface strata can dry out, 
must have xerophytic adaptations if the climate is such that drying 
out of these levels may occur. These conclusions are supported, in 


1 Warrington, R., Physical Properties of Soils, 1900, pp. 63-64. 

2 Heinrich, Jahresb. Agrik. Chem. 1875-6. p. 368. 

3 Biedermann’s Central-Blatt fur Agrik. Chem. 1885, p. 279. 









162 


MICHIGAN SURVEY, 1906. 


part at least, by the testimony of many farmers in the region under 
discussion, who report that crop plants suffer more severely from 
drought during dry times on muck or peat soils than upon other types. 
Experiments with our native plants have been planned to test the cor¬ 
rectness of these conclusions, but it is too early tp report upon them at 
this time. 

(4.) Not only must perennial plants endure, from time to time, the 
difficulties of real drought in peat bogs, but they must also be able to 
stand excessive wetness about their roots for long periods and the heath 
plants, Betula pumila , and several species of Balix and a few others 
are able to do this for at least three years without being injured, for 
the writer has had these species under observation where the water 
level has been raised more than a foot above its former height upon a 
heath bog for that length of time, and the plants still survive in a fairly 
good condition, while other species, more sensitive to water, have died. 

(5.) In the heath zones and heath swamps of the southern part of 
the Southern Peninsula of Michigan there are more species of shrubs 
and trees near the water level than in the north, and as the surface of 
the peat is drained even slightly, species of plants occupy it which 
never, so far as observed by the writer, are found in the same sort of 
habitat at the north, but grow in the dryest and poorest soils there. 

A most striking example of this is Aralia hispida Vent., which was 
a common species on the peat deposit at Chelsea, now being utilized 
for the manufacture of fuel. Proceeding northward some species leave 
the peat soils entirely and are only found upon dry and poor soils, while 
others still remain in them but only around their borders at a well- 
defined distance above water level, while others still are found a,t the 
water level as far north as observed. The following notes illustrate 
this : 

Gaylussacia resinosa is common at Ann Arbor, both in and out of 
the bogs, growing as freely on light sand as it does in the bogs, but 
not so tall. 

In Gratiot county it was rare in bogs, but very common in the dryest 
places on poor sandy soils, while in Roscommon county it was not noted 
at all in the swamps although very abundant as a sand plant. In 
Tuscola and Huron counties it occurred as a sand-dune plant. It en¬ 
dures shading well wherever found. 

Dasiphorci fruticosa (L.) Rydb., at Ann Arbor, is an occasional con¬ 
stituent of the open bog and marsh flora, in the heath zone, but occurs 
upon a very dry hillside at Lakeland and further north in Huron and 
Tuscola counties it was found only upon sandy shore lines; still farther 
north, however, it was noted in bogs, as well as on sandy soils. 

I Actinium Canadcnse, in the vicinity of Ann Arbor, is found usually, 
if not always, in the peat bogs, and in Gratiot county it is still a peat 
plant, but is found growing upon mineral soils in dry places as well, 
while in Roscommon county it is the most common sand and dry ground 
blueberry, covering sandy ridges and flats, wherever the ground was 
open enough, and was not listed from the peat bogs at all. 

Vdccinium Pennsylvanicum does not occur in the lists made by the 
writer about Ann Arbor, except at Mud Lake, as noted above. At 
Alma, Gratiot county, it is found upon the dry and sandy knolls, but 


DAVIS ON PEAT. 


163 


sometimes in tlie margins of swamps as well. In Roscommon county 
it occurs on dry sand commonly and was not noted elsewhere. 

Vaccinium corymbosum. In Southern Michigan wherever found is a 
plant of the heath association, often in the very wet part of the swamps, 
and persisting after the surface gets quite dry, and also under the 
shade of the taller shrubs and trees. At Alma it is still a plant of the 
same association, and was not seen in the bogs examined farther north, 
but in New England it grows commonly on high and dry ground as 
well as in the swamps. ' • 

Aronia arbutifoUa and A . nigra (Willd.) Britt., the latter more fre¬ 
quently, grow very commonly and with great luxuriance in many of the 
heath swamps in Washtenaw and Livingston counties. In Gratiot 
county the latter species occurred both in the peat and on dry sandy 
soils, and in Roscommon county it covered the sandy hillsides from the 
top down nearly to the water level, but was not recorded in the swamps, 
except as a straggling plant in the dryer parts. 

Ilicioicles mucronata (L.) Britton, is always a plant of the heath 
swamps about Ann Arbor, so far as observed, and is often found grow¬ 
ing in very wet Tamarack swamps in the shade, to large size. At 
Alma it was not common, but grew in wet swamps where found. In 
Roscommon county it grew only on the borders of the bogs, often form¬ 
ing a distinct zone on the mineral soil on the borders of the bogs, from 
about a foot above the water level to 3 or 4 feet above it, starting in 
above the Cassandra. In Wexford county it was found growing in a 
rather dry and shallow peat deposit, near the margin. 

Ilex verticillata is rather common in the vicinity of Ann Arbor, in 
the wet parts of peat swamps, often in the shade. It also grows well 
in other swamps and on mineral soils near the water level, where it 
endures the shade well. In Gratiot county it is very common in wooded 
and open swamps, and is not uncommon in the borders of swamps. 
In Roscommon county it was found mainly on the borders of the open 
swamps with Ilicioides, but was also found well distributed in the 
Cedar and Tamarack swamps, and was noted as growing from these 
up to a height of 3 or 4 feet above the water level on the mineral soil. 

Cassandra, as found in the south, is always a plant of peat bogs and 
of the wettest parts of these, probably never establishing itself more 
than a foot above the water level, and has not been observed in the 
region of Ann Arbor, growing on mineral soil. In Gratiot and Mont¬ 
calm counties it is usually found in the peat bogs, but at Bass Lake 
it grows well upon an ice-formed sand ridge at least three feet above 
the level of the lake, and shows in some of the bogs a tendency to grow 
above the water level. 

In Roscommon county, while it makes luxuriant growth in the swamps 
and bogs, it seems to avoid the very lowest parts of these and is found 
making well-marked fringes around the wet sedge bogs extending out into 
these upon fallen logs and creeping up the sandy banks of the Sphagnum 
swamps, where it also covers the whole surface. It was noticed well 
established near Boyce Lake as much as 4 feet above the water level, 
growing in sand, and mixing with the Sweet Fern, which covered the 
higher parts of the slopes. 

Kalmia glauca Ait. is a rather common plant in the region studied 


164 MICHIGAN SURVEY, 1906. 

and associated closely with Cassandra, but was not seen outside the 
bogs. 

Andromeda Pollfolia L. is found at Ann Arbor in the wet part of the 
heath zone, and as far as studied shows no indication of leaving the 
water level or of growing in mineral soil, for in Roscommon and Wex¬ 
ford counties it was always found as far out in the sedge zone as any 
shrubby plant. 

Betula pumila L., as it occurs about Ann Arbor, is common in the 
wet parts of the swamps and marshes in which it occurs, but persists 
after the water level has been lowered by draining and in a single case 
lias been found in a moderately dry situation growing in mineral soil, 
at least three feet above the water level. Farther north it keeps in the 
peat bogs in the very wet places and does not get above the water level. 

Myrica Gale L. was only found in Roscommon county growing in the 
wet zones of the marshes and bogs with the sedges. Farther north, 
however, it was seen frequently in sandy soil above the water level. 

Ledum Groenlandicum Oeder, the Labrador Tea, was another species 
found only in the northern part of the region studied. In Hobart bog 
it was growing in the higher levels of the Sphagnum zone and in the 
tree zone, where it bore the shade well. In the vicinity of Boyce Lake 
it was apparently more plentiful in shade than in the open, and grew 
in the better drained situations slightly above the water level and some¬ 
times in mineral soil. 

Salix myrtilloides L. and &. Candida FL, the most interesting of the 
various Willows which grow in the heath swamps show little change in 
their relation to the water level throughout the region studied, both 
keeping near the water and showing no greater tendency to grow away 
from it at the north than at the south. 

Spiraea tomentosa L., an Ann Arbor, is occasionally found growing in 
the peat bogs and more rarely on the wet shores of lakes, a foot or so 
above the level of the water. In Montcalm county this plant grows on 
the borders of a few bogs, but was not found growing in them. In New 
Hampshire the species is frequent in dry and barren pastures, where it 
takes the poorest and dryest places. 

The Tamarack, in the region about Ann Arbor and southward, is a 
bog or swamp tree, seldom occurring outside of peat deposits, and usually 
very near the water level. It has been planted on high ground in the 
city and has grown well there. In Gratiot county the tree is sometimes 
found on high ground around swamps, while on Mackinac Island it is 
found growing at all elevations and in all kinds of soil, making a fairly 
constant element in the second growth forest. 

Enough species have been cited to show the marked tendency which 
these bog shrubs and trees have to leave the bogs for higher ground and 
a type of soil where the water level is low and the soil moisture scanty, 
and to indicate that in the more southern part of their range plants may 
be confined to the bog habitat and in the northern to truly xerophytic 
conditions on mineral soil. 

From the consideration of these facts follows the conclusion that 
many, if not all the “bog xerophytes” of the peat swamps of Michigan 
are bog plants only in the southern part of their range, and that many 
of their obvious adaptations for protection against drought are needed 
in their ordinary habitat in the region of their greatest frequency and 


DAVIS ON PEAT. 


165' 


widest dispersal and these enable them to persist in bogs and swamps 
during constantly recurring dry periods towards the southern limits of 
their range. 

(C.) The plants given in the above list, many of them, have fleshy 
fruits, which are attractive to birds, and aid in securing the dispersal 
of their seeds. An observer has only to visit one of these heath swamps 
during the time when the various fruits are ripe to see how attractive 
these are in color, form and size, to the fruit-eating birds, as well as 
to man, for a little watching will show that more than one species is 
at work gathering fruit. In the late summer and early fall, the migrat¬ 
ing season, the swamps are full of birds, and flocks of robins and black¬ 
birds may be found at work in them at almost any time, but especially 
in the morning and late afternoon. In fact several species make these 
swamps regular migration routes as they move southward, and by them 
the seeds are carried from north to south each season and scattered 
where, if conditions are favorable, they will be most likely to germinate, 
namely upon thoroughly moist soil in the swamps, which keeps the 
seed coats, already softened by passing through the digestive system 
of the birds from drying again. It would seem that no other fac¬ 
tor need be considered to account for the occurrence of the great number 
of shrubs which characterize the heath swamps of Michigan. 

(7.) With the appearance of the shrubs and trees upon the sedge 
marsh, another biotic factor than tolerance of water enters into the 
matter of deciding what types of plants will finally occupy the ground. 
This is the relative need of light of the various species, or their tolerance 
or intolerance of shade. Those plants which live from year to year grow 
to different heights, and the taller ones finally overtop the shorter and 
unless these can endure shading they must succumb. An extended 
series of observations upon the woody plants growing with the Sphagnum 
upon the marshes under consideration, and others as well, establishes 
the fact that many of the species are unable to bear a weakened light, 
and as soon as shade of anv density develops in their habitat, thev dis- 
appear and their places are taken by species which will grow in the 
shade. The more aggressive species, such as Aronia nigra , are aided by 
their method of propagation, a system of long underground branches 
sent horizontally from the parent plant in every direction and these, 
at their ends and along their sides, send up vertical leaf-bearing stems 
which soon establish themselves and make new centers of dispersal. 
Such species may advance as much as six feet in a season upon any 
of the lower shrubs like Cassandra and in a few years after becoming 
established hold the entire ground. The Tamarack is taller than most 
of the plants with which it is associated upon the marshes, hence it 
shades them, and, while its shade is not dense, it seems to be effectual 
in stopping the growth of a number of species and finally exterminates 
them. Cassandra is often shaded out by the Tamarack and the only rec¬ 
ord left is that which the dead and dry stems of the lesser plant give, 
and the partly decayed debris in the peat below. The Blueberry, Ilex 
verticillata and Ilicioides mucronata on the other hand, are more tol¬ 
erant and often make large growth in the shade, the last named species 
sometimes reaching a height of 20 feet under old Tamaracks. In like 
manner the Black Spruce is a taller plant than its associated species, 
except a few trees, and makes a denser shade than the Tamarack, and 


166 


MICHIGAN SURVEY, 1906. 


under its shade few species survive, even the Sphagnums , which are able 
to get along with less light than most of the marsh plants, give way be¬ 
fore it. Again, the Tamarack seedlings cannot grow in the shade of the 
Spruce, while those of the Spruce grow readily under the Tamarack, as 
do those of the Cedar, so that often the Tamarack lasts but a single gen¬ 
eration, being succeeded by the more tolerant species. The Tamarack also 
cannot grow up in the shade of the Red Maple and Birches and other 
broad leaved species and if overtopped by them at any age, is generally 
killed, so it gives place to these species when they succeed in establish¬ 
ing themselves in competition with it, and it is either driven to wetter 
open spots farther out upon the marsh or disappears entirely. 

The Tamarack will grow under the lighter shade of Poplars and Wil¬ 
lows, and thus may succeed a growth of these species, since they do not 
live when shaded by it. 

From the foregoing discussion it is evident that the plants upon the 
surface of a peat deposit are not necessarily nor usually an indication as 
to the character of the peat below, and in general are relatively a short 
time in places where they are found. In the filled basins, and in other 
types of peat deposit as well, the character of the vegetation is certain to 
change with fluctuations of water level, which may occur as the result 
either of prolonged drought, periods of less than normal rainfall, or 
periods of excessive precipitation, the latter being especially effective 
in causing change, because plants which may have been years in estab¬ 
lishing themselves in places which they occupy, may be killed in a very 
short time of high water and the ground which they have been occu¬ 
pying thus be left free from growth of such species as are able to live 
under the new conditions. 

A change in the elevation of the outlet of the basin, if one exists, will 
produce the same effects as the variations in precipitation, drying out 
if it is lowered, and flooding if raised. 

If such an elevation of the water level is at all permanent, the whole 
cycle of plant growth may be passed through with again. Elevations of 
the water level from six inches to one foot are efficient in producing 
complete change in some of the swamp associations. 

From the lateness of appearance of the Sphagnum moss upon the 
deposit made by the water plants and the Carices it is easy to see that 
no great thickness of peat is built up by it. The height to which this 
could go on is limited by the height to which the water level may be 
raised after the appearance of the moss, or that to which it will rise in 
the Sphagnum through capillary action. Under climatic conditions 
such as prevail in Michigan, this is about 2 feet and, unless the surface 
of the peat slowly settles as consolidation of the material below the sur¬ 
face goes on, the formation of the peat ceases, so far as Sphagnum is 
concerned, at that level. In the cases where this was tested, sec¬ 
tions at Mud Lake, and at Oxford, Oakland county, show that in less 
than two feet all of the deposit which can be attributed to the moss is 
passed through. Above this deposit there may be as much as a foot of 
living moss, though usually less. 

A section made near Vestaburg, Montcalm county, through an island 
of Sphagnum gave 21 inches from the top of the living moss to the bot¬ 
tom of the moss peat, below which were 1 to 2 inches of shrub remains, 
probably Cassandra, which was still growing in the “island.” 


Geological Survey of Michigan 


Annual Report for 1906, Plate XIV 



Reaver Dam near Negaunee, Mich., shows pond and marsh along border 
Photo, by Prof. R. H. Pettit, M. A. C. 








DAVIS ON PEAT. 


167 


Below this were remains of sedge rootstocks and roots for an inch and 
at from 4 to 5 inches below the bottom of the Sphagnum was a well 
marked zone an inch or more thick with large quantities of rootstocks 
of the Yellow Pond Lily, with numbers of the seeds in the peat above. Be- 
low this, to the bottom of the section, the peat was more homogeneous, 
but was easily separable into laminae, which when split apart showed 
large numbers of the leaves of grass-like plants. 

Similar sections through the Sphagn/wm in Roscommon county, gave 
similar results. 


Deposits Formed Behind Dams. 

In the hollows which have been formed by dams of some of the types 
mentioned in a former paragraph, the effects of changes of the water 
level are shown most clearly, as in these there may be a periodical eleva¬ 
tion of the barrier to a greater height, and this in turn holds the water 
impounded back to a greater height, which at once reacts upon the vege¬ 
tation and changes the type of growth more or less completely. 

Beaver dams were probably the most common type of dam which re¬ 
sulted in the formation of peat in the region of which Michigan is a 
part. Speaking of them and their occurrence in the state Desor 1 says: 
“They cite in Michigan, rivers of considerable size which are barred 
by dams, making thus a quantity of lakes and ponds which would not 
exist without them. It is evident from this that without these dams 
the lake and peat deposits, which are found at the bottom of these 
ponds, would be less numerous. The beavers have thus exercised an in¬ 
fluence not only on the distribution of waters, and the consequent fer¬ 
tility of the soil but also up to a certain point even upon the distribu¬ 
tion of recent rock formations.” 

The importance of the beaver as an agent in the formation of peat 
in the Southern Peninsula is also mentioned at some length by Bela 
Hubbard, 2 of the first Survey, one of the keenest writers who has ever 
written upon the geology and natural history of Michigan, and even 
earlier geologists. 

In this article the writer savs: “Not one or two, but a series of such 

<L/ q 

dams were constructed along each stream so that very extensive sur¬ 
faces became thus covered permanently with the flood. The trees were 
killed and the land converted into a chain of ponds and marshes with 
intervening dry ridges. In time, by nature’s recuperative process—the 
annual growth of grasses and aquatic plants—these filled with muck or 
peat, with occasional deposits of bog lime, and the ponds and swales 
became dry again. 

“Illustrations of this beaver-made country are numerous enough in 
our immediate vicinity. In a semi-circle of 12 miles around Detroit, 
having the river for a base, and embracing about 100,000 acres, fully one- 
fifth part consists of marshy tracts or prairies, which had their origin in 
the work of the beaver. A little further west, nearly a whole township 
in Wayne county is of this character.” 

Taking the beaver dam as an illustration, since it is small, rarely 
more than 5 or 6 feet high 3 and relatively rapid in its effects, the course 


1 Desor. E., La Foret Vierge, p. 57, Paris, 1879, 57. 

2 Hubbard, B., Memorials of a Half Century, pp. 862-3, N. Y.. 1888. 

3 Melton and Cheadley. North West Passage by Land, p. 178. 



168 


MICHIGAN SURVEY, 1906. 


of development* of this type of peat deposit would depend upon the fol¬ 
lowing considerations. 

In regions of comparative flatness, the building of even a low and weak 
dam, such as beavers erect, will flood a considerable area. This is clearly 
stated by Melton and Cheadley, who report that the former operations 
of beavers in Canada must have been on a very extensive scale, for nearly 
every stream between the Pembina and the Athabasca except the large 
Macleod river appeared to have been destroyed by the agency of these 
animals. 

At one place they found a long chain of marshes formed by the dam¬ 
ming up of a stream which had ceased to exist, the beaver huts had be¬ 
come grassy mounds and the dam a green and solid bank. 

If such an area was covered at the time when the water level was 
raised by a growth of trees or shrubs, these would be killed, and some 
would be cut down by the beavers for food and construction purposes, 
the rest would decay and fall to the ground or into the water, where 
they would shortly be overgrown and buried. The destruction of this 
taller growth would enable the marsh plants bordering the stream and 
the water plants growing in it to spread out, first upon the margins 
of the flooded area, then because the water is shallow, over the whole 
impounded surface. Such an area of shallow water would fill rapidly 
with vegetable ddbris, and as reedy and grassy types of vegetation ob¬ 
tained a foot-hold and became abundant the water area would be re¬ 
stricted, until perchance, the animals built their dam higher or aban¬ 
doned it for a new place. 

In the former case there would be a new advance of water plants over 
the marsh vegetation, while in the latter, the marsh would become at 
first covered with stages or Typha and later by grasses, one of the first 
to be established being probably Calamagrostis Canadensis, the Blue 
Joint, of which stages, good examples are the so-called “beaver-mead- 
ows,” so often utilized as sources of hay by early settlers in Michigan 
and other parts of North America. At the last period as the drainage 
improved, Willows, Alders and other shrubs would appear on the sur¬ 
face and finally the forest would close in again. 

The fact that the original course of the stream had been obstructed 
by even a weak dam would tend to cause accumulations of drift mate¬ 
rial upon the obstructed area in time of floods, and eventually this might 
form such a check to the drainage that the water level might be raised 
faster than the vegetation could build up the surface. In such a 
case the tree growth would be destroyed, and again the area would be 
covered by water and marsh vegetation, to go through the cycles as before. 

In undisturbed natural conditions it is probable that the beavers 
would occupy a favorable site again and again as the surface of the de¬ 
posit was built up and their favorite food plants re-established them¬ 
selves within reach from the place where a dam could be maintained, 
and in at least two cases which have come to the writer’s notice such 
dams as these have been found in cutting into peat deposits. The first 
of these was cut through in draining a peat bog in Sec. 2, in Arcada 
township, Gratiot county, where the dam was buried under about three 
feet of peat and seemed to be about three feet high. A case of recent reoc¬ 
cupation of an old dam site by a colony of beavers was observed by the 
writer in the Northern Peninsula, where a very old dam had been rebuilt 


Geological Survey of Michigan 


Annual Report for 1906, Plate XV 



Beaver Meadow near Negaunee, Mich. Photo, by Prof. R. H. Pettit, M. A. C 











































































. 




* 







• 





















DAVIS ON PEAT. 


169 


within the present year (1906), flooding about 50 acres of Spruce and 
Tamarack woods. 

This dam was located in section 2, T. 49 N., R. 30 W., and was about 
4 feet high in the channel of the stream which was closed by it, so that 
the water level was raised to that extent. The outside of the dam was 
a tangled mass of brush, sticks and pieces of wood both freshly cut 
and in all stages of decay, the animals evidently using whatever mate¬ 
rial they found near the place. The top of the dam was about a foot wide 
and had a number of small stones placed irregularly upon it, and the 
water side of the structure was heavily plastered with mud. 

The dam was nearly water tight, only a small amount of water running 
under or through it, the greater part of that which escaped from the pond 
was going over the ends, which were slightly lower than the middle, or 
over the long side wing, built to increase the height of the water by the 
former tenants of the dam, and repaired by the present generation. The 
main structure was strong enough to bear the weight of a heavy man with¬ 
out yielding. The dam was built across the brook \Chere the valley was di- 
vided by a slight elevation, and after the main part was done, the 
builders found it necessary to construct a long wing from the elevation 
across a marshy place to the other wall of the valley. This wing was 
from 1 to 2 feet high and about 200 feet long, and the old structure 
completely overgrown by shrubs and other plants, was visible, having 
simply been repaired in the broken places and raised in the low ones, 
from the pond side, by the use of small sticks and mud. The repair 
work was apparently very frail although fairly efficient. An interest¬ 
ing feature of the main dam was the fact that the arc curved irregu¬ 
larly down the stream. Down the same valley and extending nearly up 
to the dam described was a broad flat swampy area covered with shrubs 
and sedges, with a few scattered small trees. At the lower end of this 
was another ancient dam completely overgrown but easily traced as 
a sharp ridge across the narrow part of the valley. 

Since beavers have been protected by the game laws their dams are 
becoming common in the wilder parts of the state and around Trout 
Lake Junction and other places in the Northern Peninsula, the flood¬ 
ing of timber lands and the destruction of trees upon them as well as the 
interference with railroads is reported as caused by the disturbance of 
the established drainage by these animals. 

In draining the extensive bog at Capac, near the outlet end, or the 
south end of the marsh, beaver dams were cut through in making the 
ditches which had in the uppermost 4 feet, a second 10 feet and a 
third 12 feet of peat over the top, while the section of the bog in the 
ditches, was formed of successive and superposed layers of vegetable 
ddbris showing that several times forests had been succeeded by grass 
or sedge marshes. In its final stage this deposit was a Cedar and Tam¬ 
arack swamp, with practically no natural outlet, the water which fell 
upon it either draining by seepage to the Belle river or evaporating from 
the surface. 

At present the surface of this deposit is bare of tree growth having 
been denuded by fire and cutting, and while both seedling poplars 
and certain types of bog plants are present, the most abundant plant 
when visited was a species of Polytrichum , a moss which is usually 


170 


MICHIGAN SURVEY, 1906. 


found in bogs where the surface is very dry, and which indicates the 
end of peat building. 

In either of the cases mentioned the resulting deposits of peat would, 
upon careful analysis, show a definite stratification, the strata repeating 
themselves in an order which would give a history of the deposit, with 
the remains of the more completely preserved plants identifiable. In 
such a deposit, at the bottom, might be found the roots and stumps of 
trees, above which the remains of water plants would be present to some 
thickness, then a mass of fibrous remains of the sedge and grasses, and 
possibly then the debris of mosses and shrubs, and, (showing the end of 
the cycle) roots, trunks and other tree ddbris. At Capac several strata 
containing tree remains were seen as noted above, but the opportunity 
was not offered to make a more detailed study. Where such formations of 
peat are found they show conclusively that the conditions under which 
the deposits have been formed have not been constant, but have varied, 

and in a definite order. 

« 

Conclusion. 

The foregoing discussion makes it evident that in the Southern Penin¬ 
sula of Michigan, peat is chiefly formed by plants which grow below or 
very near the water level, aquatic plants in connection with sedges, 
and other grass-like plant; Sphagnum does not appear until late in 
the history of the formation, if at all, and develops only shallow, su¬ 
perficial layers of peat and usually grows best in association with certain 
shrubs, which may become prominent before the Sphagnum appears, 
and which may also reduce its effectiveness in peat forming by develop¬ 
ing dense shade. 

The ecological factors controlling the succession of plants, which by 
their growth and decay, under the necessary conditions, form peat in the 
area under consideration have been indicated, but may be summed up 
as follows: 

(The effects of these factors on the form of organs, i. e., adaptations, is 
not here considered.) 

Light: That which may be considered of first importance, since a wet 
habitat is assumed, is the light factor, because this limits the develop¬ 
ment of peat deposits through limiting the growth of plants, both below 
and above the water level. 

Plants which make abundant vegetative growth in northern regions 
must have full light, and this is not obtainable in the deeper water in de¬ 
pressions, or in the dense shade of other species. Direct deposition by liv¬ 
ing plants therefore is limited by the depth of water through which suf¬ 
ficient light may penetrate to induce vigorous plant growth, or to develop 
such species of plants as send leaves to the surface through earlier stages 
of growth, before their leaves reach the surface, and by the amount of 
shade in which peat-forming species can develop. The water of many 
lakes in the northern part of the state, while free from sediments, is dark 
colored from dissolved organic matter, and in such lakes there is little 
vegetation to be found. 

Soil: A second group of factors of importance are those termed the 
edaphic or soil factors. Both the physical and chemical characters of the 
substratum in which the underground parts of plants grow are important 
in determining their distribution, and in many cases control the type of 


DAVIS ON PEAT. 


171 


vegetation in a given area, or account for the presence or absence of 
certain types. 

It seems probable, from the present state of our knowledge, that many 
species of the important peat-forming aquatic plants are greatly 
dependent upon- the mechanical structure, the compactness, and the pen¬ 
etrability for the roots of plants, soil-water, etc., as well as the chemical 
composition of the soil in which they grow, and it may be demonstrated 
that both species and individuals are much more numerous where 
there are beds of loose, finely divided material, rich in plant food than 
where the substratum is compact, hard and poor. This is in part due 
to the requirements of many species for abundant food, and in part to 
the greater ease with which the stems and roots penetrate the less com¬ 
pact soils; and as the stems, or rhizomes, of a large number of such plants 
are propagating organs, a favorable soil for the growth of these, favors 
the dispersal of the species over the bottom of a lake. 

Temperature: Heat is a third factor of importance, and its absence 
tends to reduce the number of species and number and the size of indi¬ 
viduals, therefore in the southern part of the state many more species 
are found in the aquatic societies than in the northern, and these are 
therefore more efficient in building up peat south than north, so that it 
may be safely assumed that the filling of lakes goes on more slowly, and 
is caused by fewer plant species in the north than in the south. 

The facts that the mean temperature of the air is lower during the 
summer season, and the periods of maximum temperature are shorter 
and fewer, cause decreased evaporation from wet soil and from 
water surfaces and render these more stable as to the water level at the 
north. This, because of the more uniform temperature, does not fluctu¬ 
ate, and changes in plant associations take place more slowly and with 
less frequency, north than south. The result is obvious in checking the 
advance of the shoreward associations to regions of high water level, 
since they chiefly advance in periods of low water, and in the less rapid 
upbuilding of the surface. 

The lower soil and water temperatures at the north also tend to in¬ 
crease the physiological dryness of the soil in the habitat under discus¬ 
sion, and its physical dryness, when once dry, because the greater 
viscosity of water at low temperatures retards percolation and thus 
make it increasingly difficult for species to establish themselves in it, 
going from south to north. 

The daily fluctuations in temperature of the air in depressions, be¬ 
cause of lack of circulation during the day, and of the downward flow 
of cold air during the night, is much greater than that upon the sur¬ 
rounding higher lands. The minimum temperature in many of these 
reaches the freezing point during every month in the growing season, 
even in the southern part of the Southern Peninsula and this fact alone 
affects the composition of the associations above the sedge zone to a very 
considerable extent, keeping out southern plants which would otherwise 
establish themselves. The species near the open water of partly filled 
lakes or growing in it, on the other hand, probably are favored by an 
even temperature, and a someAvhat prolonged growing season. 

Air: The difficulty of getting a sufficient supply of air from soil sat¬ 
urated with water or from water directly, excludes from the plant asso¬ 
ciations concerned in peat formation, all plants which do not have 
special adaptations or cannot develoo them, for the purpose of getting ox- 


172 


MICHIGAN SURVEY, 1906. 


ygen under the conditions presented. This limits the number of species 
which grow in the water, and with roots below the water level, to a 
few, and reduces the competition between types and species to a mini¬ 
mum, thus favoring good development of the types which can live under 
the conditions. Above the water level this factor still has its influence 
in excluding species which are deep rooted in favor of those which are 
shallow rooted, thus again reducing competition and simplifying the as¬ 
sociations. 

The other important influence of air which may be considered is in 
its effects as wind. In the wide stretches of open marsh or bog, plants 
are freely swept by winds both winter and summer, and transpiration 
is greatly increased therebj^, a fact which again influences the composi¬ 
tion of the plant associations growing in peat deposits with leaves ex¬ 
posed to the air, those which are not protected against excessive trans¬ 
piration being excluded in favor of those which are, and again the com¬ 
position of the associations may be simplified in number of species by 
this factor. 

The wind, on either hand, has a profound influence in aiding in the 
distribution of most aquatic plants along the shores of the bodies of 
water in which they grow and a great many of the species of this type 
are provided with adaptations which insure the transportation of propa¬ 
gating buds, fruits and seeds from one point to another by wind and 
currents created by winds, and the leeward side, which is frequently 
the eastward one, of any body of water in which plants are growing will 
give numbers of illustrations of the importance of this factor. 

Plants: After the length to which the subject has already been dis¬ 
cussed it is scarcely necessary to do more than mention that the influence 
of most species of plants upon some of those with which they are asso¬ 
ciated is important, in a greater or less degree, according to the close¬ 
ness of the association and the extent to which they have the same or 
similar requirements, since each species exerts some influence upon all 
others with which it competes for light, air, soil and water. By such 
competition species are eliminated from plant societies more frequently 
than by any other factor. 

Of even more importance in affecting the composition of plant associ¬ 
ations, and the places which these shall occupy is the influence which 
plants exert upon their habitat, by affecting drainage conditions as 
pointed out above and by concentrating mineral and other beneficial 
and noxious substances near the surface of the soil by their growth and 
decay. Each bog plant society so modifies its habitat, that sooner or 
later it can no longer hold it in competition with more aggressive associ¬ 
ations and gives way before them. This modification proceeds until the 
rate of change produced by the plants about balances the change caused 
by ordinary weathering and decay, but it is of the greatest importance 
in considering the relations of the type of plant societies which have 
been under consideration. 

The conclusions reached in this discussion, if valid for the region cov¬ 
ered by the investigation, should have a much broader application 
than is given them, and as is shown in another paper, they have proven 
valid, when applied to the conditions existing in the more northern 
region of the Northern Peninsula of Michigan and should do so for any 
other. 



GEOLOGICAL SURVEY OF MICHIGAN, 


ANNUAL REPORT FOR 1906. PLATE XVI. 


West 


Longitude g5 


Greenwich 


Whiske^^ 


Duck 


SbttrJ&l 




Lit. Summi 


= st*» 


ST- MAftTma to. i : 


ALFRED C. LANE, STATE GEOLOGIST, 


won, ig 


HINGTON 




Map of the 

Original Swamp Areas 

OF THE 

LOWER PENINSULA 
OF MICHIGAN 


^Crooked Id. 


SOUTH FT. 


Compiled from John Fanner’s Map of 1873 f° r Report by 
C. A. Davis on Peat. 


Swamp Areas in brown. 


iSTURGEON PT. 


tfei£iVmg su 


Muskrt 


-Miimsm 


Lincoln or 


Life Saving Sta. _, 

iSurlHtr^siffj&efiige- 

ih ak« b i i »nea-— 


Pc n t iftffrfil '.<$ 


FISH POIN 


LITTLE PT. SABLE 


Life Saving'Sta. 


Gragg 


Life Saving Sta, 


Life 


Kalamaitid 




-tE 943 Hig 

CANAL 


Thames M* 


izinR, 


POINTE PELCE- 


Middles*^ Itf; 


CEDAR PT. 


(Copyright 1907. by A. J. Farmer 


Old Territorial Line 


Longitud* 


imswMMHi 






!M»jir!;«k:kal.' 

m«f ■Eciaii'vn 


^•eiKvVijawi 


innsaii 




m 

* 

•1 

m 

- 

- 

- 




r- 

L 



— 

Z 

2 



— 



l 

~ 

[ 































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































DAVIS ON PEAT. 


173 




SELECT BIBLIOGRAPHY 


So many comprehensive lists of works relating to peat, its formation, 
and especially its utilization have been compiled and issued within a 
short time, that it has not been thought necessary to add another, which 
would perforce, largely duplicate those already in existence, and only 
such titles are here listed as have been especially cited or consulted in the 
preparation of this paper, or which seemed definitely to pertain to the 
problems involved in it, or to the distribution of peat bogs and peat¬ 
forming plants in the region in which most of the work of the investiga¬ 
tion has been carried on. 

s 

The annotations are intended to call attention to some especial features 
of the works to which they are appended. 


Adams, C. C. 

An Ecological Survey in Northern Michigan. 

Ann. Kept. Mich. Bd. of Geol. Surv., 1905. Lansing, 1906. 

Adams, C. C. 

The Post Glacial dispersal of the North American Biota. 
Biological Bull. IX, 1. 1905. 

Atkinson, G. F. 

Elementary Botany. New York, 1898. 

Beach, A. 

Peat Fuel. Inst. Civ. Eng. Proc. 147. 1900-1. 

Beal, W. J. 

Michigan Flora. Kept. Mich. Acad. Sci. Y. Lansing, 1904. 
Bordollo, J. 

Peat Fuel Production. Engineer XLIII. Chicago, 1906. 
Briquettes as Fuel in Foreign Countries. Special Consular Repts. 
XXVI. Washington, 1903. 

(Discusses the manufacture and use of peat and otner briquetted 


fuels in Europe.) 

Brown, F. B. H. 

Plant Societies of the Bayou at Ypsilanti, Michigan. 
Bot. Gaz. XL. Chicago, 1905. 

Brown, R. 

Our Earth and Its Story. London, 1887. 

Burns, G. P. 

Formation of Peat in Dead Lake. Rept. Mich. Acad. 


Sci. VI. 


Lansing, 1904. 

Carter, W. E. H. 

Peat Fuel, its Manufacture and Uses, 
for 1903. Toronto, 1904. 

(Full Account of Canadian Conditions 
ufaeture.) 


•Rept. Ont. Bur. Mines 
and Methods of Peat Man- 




23 


174 


MICHIGAN SURVEY, 1906. 


Chamberlin, T. C. 

Native Vegetation of Wisconsin. Geol. Surv. Wis. IT. Madison, 
1877. 

Cole, L. J. 

The St. Clair Delta. Geol. Surv. Mich. IX, Pt. 1. Lansing, 1903. 
Coulter J. M. 

Plants. Chicago, 1900. 

Coulter, S. M. 

An Ecological Comparison of Some Typical Swamp Areas. 

Kept. Mo. Bot. Card. XV. St. Louis, 1904. 

Cowles, H. C. 

The Physiographic Ecology of Chicago and Vicinity. 

Bot. Gaz. XXXI. Chicago, 1902. 

Cowles, H. C. 

The Physiographic Ecology of Northern Michigan., 

Science, XII. New York, 1900. 

Clark, H. L. 

Notes on the Flora of Eaton County, Michigan. Kept. Mich. Acad. 
Sci. III. Lansing, 1902. 

Dana, J. D. 

Text Book of Geology. 5th Ed. New York, 1897. 

Dana, S. L. 

Muck Manual. 1842. 

Daniels, F. P. 

Ecology of the Flora of Sturgis, Michigan, and Vicinity. 

Kept. Mich. Acad. Sci. IV. Lansing, 1904. 

Daniels, F. P. 

The Flora of the Vicinity of Manistee, Michigan. Kept. Mich. 
Acad. Sci. Lansing, 1904. 

Darwin, C. 

Naturalist’s Voyage Around the World. New York, 1888. 

Davis, C. A. 

Contributions to the Knowledge of the Flora of Tuscola County, 
Michigan. Kept. Mich. Acad. Sci. I. Lansing, 1900. Bot. Gaz. 

- XXV." Chicago, 1898. 

Davis, C. A. 

A Contribution to the Natural History of Marl. Jour. Geol. VIII, 
Chicago, 1901. 

A Second Contribution to the Natural History of Marl. 

Jour. Geol. VIII, Chicago, 1901. 

The Natural History of Marl. G£ol. Surv. Mich. VIII. Lansing, 
1903. 

Davis, C. A. 

The Flora of Michigan Lakes. Kept. Mich. Acad. Sci. I. Lansing, 
1900. 

Desor, E. 

La Foret Vierge. Paris, 1879. 

Desor, E. 

In Foster & Whitney’s Report on Geol. of Lake Superior Land 
District, Part 2. 1851. 








DAVIS ON PEAT. 


175 


/ 


Eiseln, J. C. 

Handbuck, order.... anleitung zur.Kentniss des Torfwesens, 

Berlin, 1S02. 

Ells, R. W. 

Peat Industry of Canada. Rept. Ont. Bur. of Mines. II. Toronto, 
1893. 


Fruh, J. and Scliroeter, C. 

Die Moore der Schweiz, mil: berucksichtigung der Gesamten 
Moorfrage. Beitr. Geol. Schweiz, Goetech. Ser. III. Bern, 1904. 
(A very comprehensive treatise on the peat deposits of Switzer¬ 
land, and a discussion of the general distribution of peat deposits 
over the earth. Has a very extensive bibliography.) 

Fruh, I. 

Torf und Dopplerit. 1883. 

Geike, A. 

Class Book of Geology. London, 1890. 

Harrington, M. W. 

Bull. C., U. S. Weather Bureau. Washington. 

Hill, E. J. 

Notes on the Flora of the Lake Superior Region. Bot. Gaz. XV. 
Chicago, 1890. 


Hill, E. J. 

The Menominee Iron Region and its Flora. Bot. Gaz. IX. Chi¬ 
cago, 1884. 

Holmes, J. A. 


Preliminary Report on the Operations of the Fuel-Testing Plant 
of the U. S. Geological Survey at St. Louis, Mo. U. S. G. S. No. 
290. Washington, 1906. 

(Reports peat tests, and has a considerable bibliography on the 
technology of peat.) 

Horton, R. E. 

In Water Resources of the Lower Peninsula of Michigan. 

W. S. & I. Papers, U. S. G. S., No. 30. Washington, 1899. 
Hubbard, Bela. 

Memoirs of Half a Century. New York, 1883. 

Jefferson, M. S. W. 

Rainfall of the Lake Country for the last Twenty-Five Years. 
Rept. Mich. Acad. Sci. VIII. Lansing, 1906. . 

Johnson, S. W. 

Peat and Its Uses. New York, 1866. 

Jukes-Brown, A. J. 

Handbook of Physical Geography. 1892. 

Kearney, T. H. _ 

Report on the. Botanical Survey of the Great Dismal Swamp 
Region. Cont. U. S. Nat. Herb. VI. 6. Washington, 1901. 

Kedzie, R. C. 


Michigan Soils. Mich. Agric. Exp. Sta. Bull. 99. Lansing, 1893. 


Roller, T. 

Die Torfindustrie. Wein, 1898. 

Kiimmel, LI. B. 

The Peat Deposits of New Jersey. Econ. Geol. and Am. Geologist, 


II, 1, 1907. 



176 


MICHIGAN SURVEY, 1906. 


Lane, A. C. 

Peat. Ann. Kept. Mich. Bd. Geol. Surv. 1902, 1903, 1904. Lansing, 
1905. 

Lane, A. C. 

Kept. Mich. Geol. Surv. VII, Pt. 2. Lansing, 1900. 

Lane. A. C. 

✓ 

Water Resources of the Lower Peninsula of Michigan. 

W. S. & I. Papers, U. S. G. S., No. 30. Washington, 1899. 
Leavitt, T. H. 

Pacts About Peat. Boston, 1867. Reprinted, Boston, 1904. 
LeConte, J. 

Elements of Geology. New York, 1896. 

Lesquereux, L. 

Torfbi ldung im grossen Dismal Swamp. 

Zeitschr. der deutsch. Geol. Gesellsch. IN'. 1852. 

Lesquereux, L. 

Origin of Coal. Ann. Rept. Penn. Geol. Surv. 1885. 

Leverett, F. 

Review of the Glacial Geology of the Southern Peninsula of 
Michigan. Rept. Mich. Acad. Sci. 'VI. Lansing, 1904. 

Leverett, F. 

The Illinois Glacial Lobe. Monograph XXXVII, IT. S. G. S. 
Washington, 1899. 

Leverett, F. 

Glacial Formations and Drainage Features of the Erie-Ohio Ba¬ 
sins. Monograph XLI, U. S. G. S. Washington, 1902. 

Livingston, B. E. 

The Distribution of Plant Societies of Kent County, Michigan. 
Ann. Rept. Mich. Bd. Geol. Surv. 1901. Lansing, 1903. 

Livingston, B. E. 

Plivsical Properties of Bog Water. Bot. Gaz. XXXVII. Chicago, 
1904. 

Livingston, B. E. 

The Relation of Soils to Natural Vegetation in Roscommon and 
Crawford Counties, Michigan. Ann. Rept. Mich. Bd. Geol. Surv. 
1903. Lansing, 1905. 

Livingston, B. E. 

The Soils and Vegetational Possibilities of the Michigan Forestry 
Reserve. Rept. Mich. Forestry Comm, for 1892. Lansing, 1903. 
MacFarlane, T. 

Moss Manure. Bull. 97. Lab. Inland Rev. Dept, of Canada, Ot¬ 
tawa, 1904. 

MacMillan, C. 

On the Occurrence of Sphagnum Atolls in Central Minnesota. 
Geol. and Nat. Hist. Surv. of 'Minn. Bull. 9, Pt. 1. Minneapolis, 
1894. 

MacMillan, C. 

On the Formation of Circular Muskeag in Tamarack Swamps. 
Bull. Torr. Bot. Club. XXIIT. New York, 1896. 


DAVIS ON PEAT. 


T77 


Michigan State # Board of Agriculture Reports. 

Peat Analysis ? 65. 

Peat Deposits of Wayne County, ’55. 

Peat Deposits of Monroe County, ’55. 

Peat Deposits of Michigan, ? 53. 

Peat as a Fertilizer, ’78. 

Peat vs. Muck, ’86. 

Peat Swamps After Drainage, ’86. 

Peat Swamps, Improvement of, ’86. 

Mills, W. M. 

A Physiographic and Ecological Study of the Lake Eagle Region, 
Ind. Ann Rept. Dept. Geol. & Nat. Resources of Ind. XNYIII. 
Indianapolis, 1905. 

Morgan, L. H. 

The American Beaver and His Works. 1868. 

Parmelee, C. W. & MacCourt, W. E. 

A Report on the Peat Deposits of Northern New Jersey. 

Ann. Rept. State Geologist of N. J. for 1905. Trenton, 1906. 

(Has many analyses and a bibliography.) 

Parsons, A. L. 

Peat, Its Formation, Uses and Occurrence in New York. 

Ann. Rept. of the State Geologist XXIII. Ann Rept. State Mu¬ 
seum, LVII. Albany, 1904. (Has many analyses and a bibliog¬ 
raphy.) 

Pennington, L. H. 

Plant Distribution at Mud Lake (Washtenaw county, Mich.) 

Rept. Mich. Acad. Sci. A III. Lansing, 1906. 

Pettee, E. E. 

Plant Distribution in a Small Bog. Rept. Mich. Acad. Sci. All. 
Lansing, 1905. 

Pieters, A. J. 

Plants of Lake St. Clair. Bull. Mich. Fish Comm. II. Lansing, 

1904. 

Pond, R. H. 

Influence of Soils on the Growth of Aquatic Plants. 

. Rept. U. S. Fish Comm. 1903. Washington, 1905. 

Reed, H. S. 

The Ecology of a Glacial Lake. Rept. Mich. Acad. Sci. til. Lan¬ 
sing, 1902.* Bot. Gaz. XXXV, Chicago, 1902. 

Ries, H. 

Uses of Peat and Its Occurrence in New York. 

Ann. Rept. State Geologist XXI. Albany, 1903. (Has analyses 
and bibliography.) 

Russell, I. C. 

A Geological Reconnaisance along the North Shore of Lakes Huron 
and Michigan. Ann. Rept. Mich. Bd. Geol. Surv., 1904. Lansing, 

1905. 

Russell, I. C. 

The Menominee Region. Ann. Rept. Mich. Bd. Geol. Surv. 1906. 
Lansing, 1907. 


MICHIGAN SURVEY, 1906. 


Schimper, A. F. W. 

Plant Geography on a Physiological Basis. Trans, 
ford; 1903. 

Scott, W. B. 

Introduction to Geology. New York, 1897. 

Shaler, N. S. 

Fluviatile Swamps of New England. Am. Jour.. 
XXXIII, 1887. 


by Fisher. 


Sci. 


III. 


Ox- 


Ser. 


Shaler, N. S. 

Fresh Water Morasses of the United States. Ann. Kept. U. S. 


G. S., X, Pt. 1. Washington, 1S90. 

Shaler, N. S. 

Origin, Distribution and Commercial Value of Peat Deposits. 
Ann. Kept. U. S. G. S., XVI, Pt. IV. Washington, 1895. 

Shaler, N. S. 

Peat and Swamp Soils. Ann Kept. U. S. G. S. XII. Washington, 
1891. 


Shaler, N. S. 

Swamps of the United States. Science VII. 1880. 

Slierzer, W. H. 

Geological Report on Monroe county, Michigan. Kept. Mich. Geol. 
Surv. VII, Pt. 1. Lansing, 1900. 

Smyth, B. B. 

The Closing of Michigan Glacial Lakes. 

Trans. Kansas Acad. Sci. XV., Topeka, 1898. 

Towar, J. D. 

Mich. Agric. College Exp. Sta. Bull. 181. Lansing, 1900. 
Transeau, E. N. 

The Bogs and Bog Flora of the Huron River Valley. Bot. Gaz. XL, 
XLI. Chicago, 1900. 


Transeau, E. N. 

Climatic Centers and Centers of Plant Distribution. 
Kept. Mich. Acad. Sci. VII. Lansing, 1905. 
Transeau, E. N. 


Forest Centers of Eastern North America. Am. Nat. 


XXXIX. 


Boston, 1905. 

Transeau, E. N. 

On the Geographic Distribution and Ecological Relations of the 
Bog Plant Societies of Northern North America. Bot. Gaz. XXXVI. 
Chicago, 1903. 

United States Department of Agriculture, Bureau of Soils. 

Soil Survey of the Alma Area, Michigan, Washington, 1905. 

Soil Survey of the Munising Area, Michigan, Washington, 1905. 
Soil Survey of the Owosso Area, Michigan, Washington, 1905. 

Soil Survey of the Pontiac Area, Michigan, Washington, 1904. 

Soil Survey of the Saginaw Area, Michigan, Washington, 1905. 
(These surveys all have maps showing the distribution of the soil 
types and swamps for the given areas.) 


DAVIS ON PEAT. 


179 


United States Consular Reports. 

Nos. 45, 49, 482, 224, 230, 248, 252, 250, 201, 200, 208, 271, 275, 279, 
281, 285, 280, 287, 291, 292, 290, 297. (These numbers contain more 
or less extended notes regarding peat utilization in foreign coun¬ 
tries.) 

Utilization of Peat on a Large Scale. 

Engineering, May 12, 1905. 

Warrington, R. 

Physical Properties of Soils. 1900. 

Weld, L. H. 

A Peat Bog and Morainal Lake. Bot. Gaz. XXXVII. Chicago, 
1904. 

Wheeler, W. H. 

The Fens of Lincolnshire. 2nd Ed. 1890. 

Whitford, H. N. 

The Genetic Development of the Forests of Northern Michigan. 
Bot. Gaz. XXXI. Chicago, 1901. 


Winchell, A. 

Geological Survey of Michigan for 1860. Lansing, 1801. 

Winchell, A. 

In Tackabury’s Atlas of the State of Michigan. 2nd Ed. 1884. 
Also in Proceedings A. A. A. S. Troy meeting, 1870. 

Winchell, N. H. 

Glacial Lakes of Minnesota. 

Geol. Soc. of America. Bull XII. 








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